Lab Values And Vital Signs As Clinical Monitoring Tools For Patient Safety

Editor's note: This text-based course is a transcript of the webinar, Lab Values and Vital Signs as Clinical Monitoring Tools for Patient Safety, presented by Adele Myszenski, PT, MPT.

*Please also use the handout with this text course to supplement the material.

Learning Outcomes

• After this course, participants will be able to evaluate why lab values and vital signs are essential clinical tools for determining the appropriateness of acute care rehab intervention and for supporting participation in occupation.
• After this course, participants will be able to analyze the normal values for BP, HR, SaO2, Hemoglobin, Potassium, Glucose, Platelets, Troponin, CPK, and other lab values while also analyzing the effects of abnormal lab values, including precautions and monitoring techniques.
• After this course, participants will be able to evaluate when to implement, modify, or hold rehab interventions based on assessment of lab values and vital signs.

Introduction

I’m based at Henry Ford Hospital in Detroit, Michigan, and I always like to start with a brief introduction to give you a sense of the setting I come from. We’re a Level 1 Trauma Academic Medical Center with a substantial ICU presence, alongside a robust general medicine service.

Laboratory diagnostic tests are an essential component in assessing a patient's overall health, particularly in the acute care setting. These tests evaluate critical organ systems, including the kidneys, liver, thyroid, and heart, among others. In acute care, some of the most frequently encountered blood tests during medical record review include the complete blood count (CBC), the differential, and the basic metabolic panel (also known as routine chemistry).

Importance of Understanding Lab Values: Normal and Abnormal

Normal values for these tests are generally based on the results observed in 95% of a healthy reference population. However, it’s important to recognize that normal ranges can vary depending on factors such as age, sex, race, and other individual characteristics. As rehabilitation therapists, we must be familiar not only with typical lab values and vital sign norms but also with how to monitor and interpret a patient’s physiological responses.

Laboratory results and vital signs form a crucial part of our clinical decision-making process during chart review. In a 2013 article, Dr. Amy Pollack and colleagues emphasized that patients experiencing acute illness require timely, accurate assessment and appropriate modification of activity by the treating physical or occupational therapist. This includes tailoring interventions to accommodate fluctuations in physiologic status.

Acute care therapists must choose interventions that optimize a patient’s performance, particularly across the oxygen transport system, musculoskeletal system, and neuromuscular system. Equally important is our understanding of the negative consequences of prolonged bed rest and the ways medical conditions can influence both physical function and cognition.

Furthermore, we must be able to recognize abnormal values—what they mean, and how they inform the care we provide. This webinar draws from a variety of sources, with evidence-based practice serving as the foundation of our clinical recommendations. Wherever possible, we’ve incorporated evidence-based guidelines relevant to a range of clinical situations, aiming to support sound and informed clinical judgment.

It's also vital to understand what constitutes a critical value. While most lab and vital sign parameters do not have strict cutoff points—or "hard stops"—there are more commonly what we consider "soft stops." For example, a borderline result may be flagged as critical based on clinical context.

Two useful definitions of a critical value help guide this understanding. In 2007, Lundberg defined it as a "physiologic state at such variance with normal as to be life-threatening unless something is done promptly, and for which corrective action can be taken." More recently, Pagana and colleagues described it as "an immediate health risk to the individual, requiring action on the part of the ordering physician."

As we assess lab results, it's important to consider whether a given value represents a red flag—something that warrants a pause or reassessment before proceeding with patient care.

When it comes to abnormal lab values and determining the appropriateness of rehabilitation interventions, many of the recommendations I'll share today are drawn from expert physician opinion. That’s because, for several lab parameters, high-quality research is still limited. You may also work alongside physicians who use their own institution-specific guidelines, and many of the general recommendations you'll hear today are exactly that—generalizations. It’s critical to have open, professional dialogue within your clinical team and to avoid using these values as strict “hard stops.”

Resources

To support this presentation, I’ve pulled from several trusted resources. First is the Lab Values Interpretation Resource, which was developed jointly by the APTA’s Academy of Acute Care and the Academy of Pediatrics. Today, we’ll focus specifically on adult parameters. This resource is comprehensive, detailed, and freely available to both OTs and PTs, regardless of APTA membership. A link is provided in the references section. Notably, all recommendations within this document are symptom-based rather than prescriptive, meaning they do not provide exact cutoff values for deferring or modifying treatment.

Another valuable resource is the Adult Vital Signs Interpretation Guide, published by the APTA in 2021 and available on their website. Lastly, I’ll be referencing the internal lab values manual developed at my institution, Henry Ford Hospital. This manual has evolved continuously over the past 25 to 30 years. It blends symptom-based guidelines with select numeric parameters, incorporating both clinical evidence and physician expertise. At Henry Ford, we prioritize a focused set of lab values that have direct implications for a patient’s medical stability.

For example, we do not typically defer PT or OT solely due to abnormal hematocrit or BNP levels. Instead, we closely monitor three core lab values across all patients: hemoglobin, potassium, and glucose. When these are out of range, it's often a signal that other lab values may be as well.

In this webinar, we’ll concentrate on lab values commonly seen among general unit patients rather than those in critical care. It’s important to remember that this content is meant to serve as guidance. All lab values and parameters presented today should be incorporated into your broader clinical decision-making process.

As we define key terms, review guidelines, and explore case examples, I encourage you to reflect on how these concepts apply to your own practice. During your initial chart review, pay close attention to lab and vital sign trends over time. Equally important is your ability to monitor a patient’s physiological response during therapy. For instance, you may need to reconsider treating a patient with abnormal vitals if you don’t have access to a blood pressure monitor, or if you're still developing confidence as a new graduate balancing lines, drains, Foley catheters, and all the nuances of an acute care setting.

In contrast, a more seasoned therapist may be better equipped to manage those complexities while simultaneously watching for subtle signs of physiological distress—changes in mentation, excessive sweating, or signs of intolerance to activity.

Other Considerations

Additional clinical considerations should always be considered in your decision-making. For instance, recent meals, IV infusions, or medications can affect lab values. Chronic conditions, such as anemia, may be well-tolerated during activity in some patients, while a sudden and significant drop in hemoglobin or hematocrit could signal a medical emergency.

Throughout this discussion, we’ll explore each key lab value in greater detail, always emphasizing that the clinical picture must be interpreted in context. That’s why clinical reasoning is at the heart of safe, effective practice. A foundational understanding of labs and vitals empowers you to perform a thorough medical record review, recognize significant trends, and engage in informed discussions with your team.

Documentation

Before diving into specific lab values, let’s briefly address documentation. As you make clinical decisions—both before and during interventions—it’s essential to document clearly and specifically. If you’ve consulted with the medical team and decided to proceed with treatment despite abnormal values, record your rationale, the parameters involved, and the patient’s response. Note any modifications made to your treatment approach. For example, if you conducted ADLs in a seated position due to orthostatic changes in blood pressure, be sure to include that context.

Lastly, when documenting vital signs during a session, always include the patient's position at the time of measurement and describe the activity they were engaged in. This detail provides important clinical context and supports sound clinical judgment.

Vital Signs

A solid baseline understanding of vital signs is essential in acute care, especially when lab values are abnormal. Normal resting vitals not only help confirm medical stability but also inform your decision to proceed, modify, or defer therapy on any given day. Resting values offer insight into a patient’s readiness for physical or occupational therapy, while monitoring during treatment can assess their hemodynamic and oxygenation response.

Vital signs should be monitored during specific situations to assess for adverse reactions, specifically related to blood transfusions or medication adjustments, and continuous monitoring of vital signs should occur for interventions in the intensive care unit.

Vital Signs (VS) at Rest

Normal resting values:

• Heart rate (HR): 50–120 beats per minute

• Systolic blood pressure (SBP): 80–180 mmHg

• Diastolic blood pressure (DBP): 40–110 mmHg

• Respiratory rate (RR): 12–18 breaths per minute

• Oxygen saturation (SpO₂): >90%

These are general population norms. Before beginning a session, always review the most recent vital signs in the chart and compare them to the patient's established clinical baseline. Ask yourself:

• Does this patient usually run hypertensive or hypotensive?

• What’s their typical resting heart rate?

• Do they require supplemental oxygen?

Examples

Here are a couple of examples of what you might see in your medical record for vitals. While your nursing staff may not document activity and positioning specifically, as I've instructed you to, you should assume that they were all taken at rest and likely in bed.

In this case, the patient's blood pressure is 88 over 45, which is concerning since the patient tends to have higher blood pressure. However, the most recent record was 113 over 56, which could be considered normal.

In this example, it's not just important to look at the latest and last; this patient actually trends closer to the last blood pressure of 94/52 than the 125/71, even though both are within normal limits. So if you were going to see the patient at 125 over 71, you may want to ask yourself, "Is this normal for this patient?" However, it is still within normal ranges.

Exceptions

There are exceptions to normal resting values that you should consider when deciding whether to proceed with or defer treatment. This is not an exhaustive list, but it highlights some common scenarios.

For instance, some surgical patients or those with bleeding risks, such as individuals who have undergone repair of an aortic aneurysm, may have intentionally lower systolic blood pressure or mean arterial pressure (MAP) targets. (Recall that MAP is the average pressure in a patient’s arteries during one cardiac cycle, typically calculated using both systolic and diastolic values.)

Patients recovering from ischemic stroke often exhibit permissive hypertension. In such cases, systolic blood pressures up to 220 mmHg and diastolic pressures up to 110 mmHg may be acceptable. Therapy should not be withheld solely based on these readings. 

Again, consultation with your clinical team is essential. Document any patient-specific permissible ranges to support your clinical decisions.

In cases of chronic hypotension, a MAP goal of 55 mmHg or greater may be appropriate. Patients with COPD might have target oxygen saturation levels as low as 88%, or even 85%, depending on physician guidance. Always consult the chart and speak with the care team to determine what is considered normal for each individual.

In some instances, heart rates up to 130 bpm at rest or up to 150 bpm with activity may be acceptable, particularly in patients with underlying cardiopulmonary conditions, cancers or metabolic diseases.

The key takeaway is individualized care. Avoid applying a blanket standard across all patients. While general resting values are helpful, they are not absolute.

Chart Review: Key Questions to Ask

When vital signs fall outside typical guidelines, that alone doesn't justify deferring treatment. Use clinical reasoning. As you review the chart, ask yourself:

• What is the trend over the last 24 hours?
• Is the patient symptomatic or stable?
• What was the patient's position during measurement—supine, seated, or standing?
• Which limb was used? Was it appropriate?
• Could any external factors be influencing these readings?

Common contributors to elevated vitals include caffeine intake, smoking, stress, pain, agitation, and delirium. These influences are often transient but must be factored in.

Medication timing is another crucial consideration. For example, if antihypertensive drugs were recently administered, you may need to delay your session to avoid compounding their effects.

The same applies to resting heart rates that exceed standard ranges. Before making a decision, consider whether any interventions could improve tolerance.

Ask yourself:

• Is the patient in significant pain that may be driving an elevated heart rate?

• Could the nurse pre-medicate with pain or anti-anxiety medication?

• Are non-pharmacological strategies like suctioning or repositioning indicated?

Before fully deferring treatment, recheck the patient’s vital signs, especially if an intervention or adjustment has been made. Next, reflect on your goals for the session. Could the patient tolerate a modified version of your planned activities?

Always aim to create the most supportive clinical environment possible. Your decision to proceed, modify, or defer should be based on a careful balance of current clinical data, patient presentation, and session objectives.

Example

For example, you might need to adjust your session by modifying the activity. Rather than ambulating the patient to the bathroom, you could complete hygiene tasks at the sink or shift to bedside activities of daily living (ADLs). Depending on the patient's condition, even seated edge-of-bed ADLs might be more appropriate.

Always weigh the risk-to-benefit ratio. Ask yourself: Will proceeding increase clinical risk, or might delaying therapy pose a greater risk to the patient’s function and recovery?

To support these decisions, I’ve included screenshots from the Vital Signs Interpretation Resource in your handout, highlighting examples of normative data, such as blood pressure classifications. According to this resource, a typical resting blood pressure is considered to be less than 120/80mmHg.  

However, remember that most patients in an acute care hospital are not in their normal baseline state. Because of this, additional clinical guidelines—tailored to the patient’s status—are often more relevant.

Another snapshot from the same resource outlines expected changes in blood pressure and heart rate during activity. This is particularly helpful when monitoring a patient in real time, not just reviewing their chart beforehand. In these cases, vital signs can guide session modifications rather than determine whether therapy occurs at all.

For example, we generally do not want to see systolic BP rise more than 20–30 mmHg, or diastolic BP shift more than 10 mmHg, with activity. Similarly, heart rate should not increase by more than 20 beats per minute, though we use a slightly more generous threshold of 30 bpm at Henry Ford.

So, if a patient’s resting HR is 80 and it spikes to 130s during light ambulation, that rapid increase could be a sign that the patient is not tolerating the session well.

While normal values provide useful guidance, they are not definitive. Even if vitals fall within standard ranges, you may still need to modify or pause treatment. Clinical decision-making is nuanced and depends on the total picture—trends over the last 24 hours, consistency of readings, and any signs or symptoms of intolerance. As you review the patient’s chart, continually ask: What is the trajectory? Has their physiological status remained stable or shifted significantly?

Vital Signs as a Reason to Defer

For instance, consider a patient whose systolic/diastolic blood pressure reads 120/80 mmHg in the morning, then increases to 140/90 in the afternoon, and most recently trends upward to 180/100 over subsequent readings. Although each value technically falls within general clinical guidelines, the gradual upward trend is concerning. This progression suggests a change in physiologic status, and it may be appropriate to consult with the medical team before proceeding with therapy.

The same principle applies to sudden or significant drops in vital signs—rapid changes in either direction can indicate instability.

At Henry Ford, we follow a set of clinical indicators that guide us when working with patients. You’ll see these referenced throughout our discussion of lab values as well. If any of the following symptoms occur during a session, therapy should be terminated:

• Dizziness that does not resolve within 60 seconds of standing upright
• An increase in heart rate by more than 30 beats per minute from baseline
• A change in systolic BP of more than 30 mmHg
• A change in diastolic BP of more than 10 mmHg

While we expect systolic pressure to rise somewhat with exercise, diastolic pressure should remain relatively stable. A significant diastolic change may signal that the patient is not tolerating the activity, and the session should be paused or stopped accordingly.

Other signs that warrant immediate cessation of treatment include:

• Blurred vision
• Dilated pupils
• Chest pain (angina)
• Shortness of breath

These more obvious symptoms and the subtler physiological cues mentioned earlier require your close attention. They may be the first indicators that your patient is not tolerating the intervention as well as expected.

Vital Sign Guidelines

It’s essential to continuously assess hemodynamic and oxygenation responses during interventions and recovery. Accurate measurement is key.

If you're looking to sharpen your manual skills, there are helpful instructional videos available online from the Academy of Cardiovascular and Pulmonary Physical Therapy that demonstrate how to take blood pressure and heart rate manually. I’ve included the hashtag #VitalsAreVital, which you can use to search for those videos. The videos were created initially as a student resource but are useful for clinicians at all levels. It offers step-by-step guidance on proper technique and interpretation.

Vital Sign Accuracy 

Accurate measurement of vital signs is critically important. You wouldn’t want to defer a patient’s session based on a reading you weren’t confident in. To help ensure accuracy, I will walk through a few key points, some of which are covered in your handout.

• First, avoid placing a blood pressure cuff on an extremity with a dialysis fistula. This may seem obvious, but it's worth reinforcing.
• Second, choose the correct cuff size. A cuff that’s too small on a larger arm can produce falsely elevated readings, while one that’s too large may result in blood pressure values that are inaccurately low.
• If a cuff must be placed on the leg, the ankle is recommended. Ideally, this measurement should be taken while the patient is lying in bed, with the leg positioned at the level of the heart. Be aware that SBP will be higher than a reading on the arm; DBP should be the same.
• Note: you cannot accurately check orthostatics with a leg cuff (because that requires you to stand the patient, and it would not be accurate if you do a leg blood pressure while they are standing)

Because vital sign readings are patient-specific, consistency is key. If you begin the session by taking a blood pressure reading on the leg, and you plan to reassess later to evaluate tolerance or response, make sure to repeat the measurement in the same location and position. This allows you to accurately compare systolic and diastolic changes over the course of your intervention.

These days, most of us rely on electronic blood pressure cuffs for routine monitoring. However, it’s important to understand their limitations. Readings can be inaccurately elevated if the patient talks, coughs, or moves their arm during the measurement.

For patients with very high or very low blood pressure, you may want to opt for a manual cuff instead. Manual measurements are more accurate in these scenarios, especially when electronic monitors are prone to error.

Specifically, electronic machines often overestimate blood pressure when it’s low, and underestimate it when it’s very high. In clinically unstable patients, this can impact decision-making, so choose your measurement method carefully.

Here are a few additional tips to help ensure accuracy when measuring vital signs:

For patients with cold extremities or circulatory disorders, pulse oximeter readings—whether for heart rate or oxygen saturation—may be unreliable when taken at the fingertips. If you're using a finger probe and the readings seem inconsistent, consider warming the patient’s hand with a heat pack or placing the probe on the earlobe, which can yield more accurate results in these situations.

When using a stethoscope to assess blood pressure manually, make sure the earpieces are angled forward, following the natural direction of your ear canals. This positioning improves sound conduction and makes distinguishing the auditory cues you're listening for easier.

As you inflate and gradually deflate the cuff, the first Korotkoff sound—the initial rhythmic tapping—marks the systolic pressure, indicating blood flow has just resumed in the artery. As you continue to release pressure, the sounds will eventually fade. The point at which the sound completely disappears marks the diastolic pressure, reflecting the moment the artery is fully open and blood flow is no longer restricted.

Orthostatic Hypotension

I wanted to include a brief discussion on orthostatic hypotension, even though it's not technically a lab value. While this measurement is often ordered by a physician and performed by nursing staff, physical and occupational therapists may also be responsible for assessing orthostatics when clinically indicated.

Orthostatic hypotension is defined as a drop in systolic blood pressure of ≥20 mmHg or a drop in diastolic pressure of ≥10 mmHg that occurs within three minutes of standing. In other words, it’s the opposite scenario from what we discussed earlier—rather than an abnormal rise in vitals, we’re looking for an abnormal decrease.

To assess for orthostatic changes, measure the blood pressure and heart rate at each position change:

1. Begin with the patient lying supine.
2. Then have them move directly to standing and take a second reading within one to three minutes.

Note: This process has changed in recent years. It was previously standard to assess from supine to sitting, followed by sitting to standing. The updated guideline now favors going directly from supine to standing, unless the patient cannot tolerate it. The alternative is to go from supine to sitting if the patient is unable to stand. 

Again, you will begin by taking the patient's blood pressure while lying supine, followed by another reading within one to three minutes of standing. You're monitoring for a drop in systolic pressure of 20 mmHg or more or a drop in diastolic pressure of more than 10 mmHg—the defining thresholds for orthostatic hypotension.

In addition to numerical changes, observe for clinical symptoms that may indicate poor tolerance to positional changes.

These include:

• Lightheadedness
• Diaphoresis (sweating)
• Dizziness
• Confusion
• Blurred vision

If you notice either significant blood pressure changes or the presence of these symptoms, it's likely the patient is experiencing orthostatic hypotension

Clinical Examples 

I have a couple of clinical examples before we move on to lab values.

Figure 1. Patient Vitals Table (3/25-3/27) 

In Figure 1, we want to carefully consider the context of the available blood pressure readings. You’ll notice that six different blood pressure measurements have been taken throughout the day, with the most recent reading showing 87/59 mmHg.

Some electronic medical records (EMRs) will flag abnormal values using visual indicators—like red highlights—to draw attention to potentially critical changes. But rather than reacting to a single number, you should ask yourself a few key questions:

• What position was the patient in when the measurement was taken?
• Had any blood pressure medications recently been administered?
• Were there any symptoms associated with the reading?

These are questions you may need to clarify with the nurse before proceeding.

In a situation like this, I would take the patient’s vital signs myself before beginning treatment. A reading of 87/59 wouldn't necessarily be an automatic reason to cancel the session—but I would want to confirm, for example, whether the value was taken while the patient was lying down, whether there have been recent clinical issues, and whether antihypertensive medications were administered shortly before.

Without that context, you’re missing critical information that should inform your clinical decision-making.

Figure 2. Clinical Example of a Patient's Vitals Table (03/25-03/28)

Figure 2. is another example involving vital signs. In this case, both heart rate and blood pressure are fluctuating, though the readings were likely taken by the RN while the patient was at rest.

Looking at the third line, you’ll see the patient’s most recent heart rate is 131 bpm. That value exceeds the typical upper threshold of 120 at rest, suggesting the patient may be in a heightened physiologic state. In this context, it may not be the right time to initiate activity or exercise, especially if this elevated heart rate represents an ongoing trend.

Additionally, the patient is tachypneic, with a respiratory rate of 23 breaths per minute, which is above the normal resting range of 12 to 18. This further supports the decision to pause or reassess before engaging in therapy.

Lab Values

Hemoglobin

Many of you are likely already familiar with the basics: hemoglobin is the primary component of red blood cells and plays a critical role in oxygen and carbon dioxide transport throughout the body.

Normal Hemoglobin Ranges

Normal values for hemoglobin differ by sex:

• Women: 12–16 grams per deciliter (g/dL)

• Men: 14–18 g/dL

This difference is generally attributed to variations in body size and muscle mass, though hemoglobin levels can also decline significantly in elderly patients, regardless of gender.

Clinical Implications of Low Hemoglobin

There are several causes of low hemoglobin, with hemorrhage and blood loss from surgery or trauma being the most common. However, other medical conditions and nutritional deficiencies may contribute as well, including:

• Vitamin B-12 and Iron Deficiency
• Bone Marrow suppression
• Oncologic conditions
• Metabolic disorders
• Various diseases can impact RBC production
• Medications

Physiologically, low hemoglobin reduces the oxygen-carrying capacity of the blood. To compensate, the body increases heart rate and cardiac output, placing additional strain on the cardiovascular system. As a result, patients with low hemoglobin may experience:

• Decreased activity tolerance/endurance

• Fatigue

• Orthostatic hypotension

• Tachycardia

• Pallor

• Dysrhythmias

Safety Guidelines for Therapy

Evidence suggests that therapy is generally safe for patients with hemoglobin ≥8 g/dL, without significant risk of adverse events. The APTA Acute Care Academy guidelines support a symptom-based approach, emphasizing the importance of monitoring vital signs to evaluate tissue perfusion during activity.

At Henry Ford, we follow more specific thresholds:

• <7.0 g/dL: Hold therapy (unless patient declines transfusion, then we consult with the medical team)

• 7.1–7.9 g/dL: Clarify activity orders and monitor closely (check heart rate and blood pressure pre-, mid-, and post-treatment and any other signs of adverse reaction to activity)

• ≥8.0 g/dL: Proceed with routine therapy

Keep in mind that some patients may have chronically low hemoglobin levels and tolerate activity better than others. For example, someone with a baseline hemoglobin below eight due to a chronic condition may respond more favorably than a post-op patient whose hemoglobin has acutely dropped to that same level.

Red Flags for Termination

If the patient exhibits any of the following signs, the session should be stopped immediately:

• Dizziness that doesn’t resolve

• Heart rate increase >30 bpm from baseline

• Diastolic BP change >10 mmHg

• Systolic BP change >30 mmHg

• Blurred vision

• Dilated pupils

• Anginal pain

• Shortness of breath

These signs indicate that the patient is not tolerating the intervention well.

Blood Transfusions and Therapy Timing

Every institution has its own criteria for transfusions. Generally, in asymptomatic general medicine patients, transfusions may be ordered when hemoglobin drops below 7 g/dL. However, in oncology or hematology populations, the medical team often determines thresholds case-by-case. Note: For patients with hematological disorders, oncological disorders, and severe thrombocytopenia, or chronic transfusion-dependent anemia, no standard transfusion threshold recommendation is available. Postoperative patients, particularly those in cardiac or orthopedic care, may be transfused once hemoglobin falls to 8 g/dL.

At Henry Ford, if a patient is receiving a transfusion:

• We do not initiate therapy during the first 30 minutes of each bag of blood
• Nurses must monitor for transfusion reactions every five minutes, making mobility during this time impractical and disruptive.

Therapy may proceed once the 30-minute monitoring window has passed and provided the hemoglobin level is at least 7.1 g/dL. During treatment, we continue to monitor blood pressure pre-, mid-, and post-intervention, treating the blood transfusion line as we would any other active IV, keeping it securely in place throughout care.

Hematocrit

At Henry Ford, hematocrit is not a required lab value to review for every patient; however, it can still provide clinically relevant information in certain circumstances.

Hematocrit represents the percentage of whole blood composed of red blood cells, and it can be a helpful indicator of fluid balance and blood loss. While we may not routinely monitor hematocrit, it may be important to review in specific clinical contexts, such as in cases of dehydration, overhydration, or acute bleeding.

Normal hematocrit values are:

• Men: 45–52%
• Women: 37–47%

Critical values are defined as:

• Less than 15% or
• Greater than 60%

These extremes are rare but clinically significant. According to the Academy of Acute Care Physical Therapy, patients should not be seen for therapy if their hematocrit levels fall into the critical range, due to the risk of cardiac failure with low levels or spontaneous blood clotting with high levels.

When hematocrit is below normal but not critical, the recommendation is to proceed cautiously and monitor vital signs closely to assess for adequate tissue perfusion, similar to the guidance for low hemoglobin. Hematocrit <25%: Use a symptom-based approach to determine the appropriateness of mobilization. Collaborate with the interprofessional team to assess the need for and timing of blood transfusion prior to initiating physical or occupational therapy.

As mentioned earlier, if you’re seeing a low hematocrit, you’re likely also seeing a low hemoglobin value, so the clinical reasoning and monitoring strategies will generally align.

Oxygen, Partial Pressure (PaO2)

The next lab value to consider is the partial pressure of oxygen, or PaO₂. While this measure is most commonly associated with patients on mechanical ventilation, I’m including it here because it can also have implications for general care patients.

If you're reviewing a chart and notice that PaO₂ is being drawn, this may serve as a clinical signal: the patient is likely having difficulty maintaining adequate oxygenation. This could suggest a worsening respiratory status and may indicate that the patient is approaching the need for supplemental oxygen or even ICU-level care. In short, seeing this lab ordered on a general unit could be your early indicator that the patient is not doing well.

What is PaO₂?

PaO₂ measures the oxygen tension in arterial blood, in contrast to pulse oximetry (SpO₂), which indirectly estimates oxygen saturation through peripheral tissues. This lab is obtained via arterial blood gas (ABG) testing, giving you a direct measurement from the bloodstream.

Determines tissue oxygen supply, along with hemoglobin and blood supply.

Normal PaO₂ values are greater than 80 mmHg. 

Causes of Decreased PaO₂

A reduced PaO₂ can result from several underlying mechanisms, including:

1. Ventilation/Perfusion (V/Q) Mismatch:

• Chronic Obstructive Pulmonary Disease (COPD)

• Asthma

• Atelectasis

• Pulmonary embolism

• Pneumonia

• Interstitial lung disease

• Airway obstruction (e.g., foreign body)

• Shock

2. Alveolar Hypoventilation:

• Kyphoscoliosis

• Neuromuscular diseases

• Head injury

• Stroke

3. Drug-Induced Hypoventilation:

• Barbiturates

• Opioids

The Oxygen Dissociation Curve

To illustrate how oxygen is carried in the blood and delivered to tissues, let’s examine the oxygen dissociation curve—a graphical representation of the relationship between the partial pressure of oxygen in arterial blood (PaO₂) and the percentage of hemoglobin saturated with oxygen (SpO₂).

Imagine the curve as an S-shaped line. The horizontal axis represents PaO₂, measured in millimeters of mercury (mmHg), while the vertical axis shows oxygen saturation, or SpO₂, expressed as a percentage.

At PaO₂ values of 80 mmHg and above, the curve flattens toward the top. This upper plateau corresponds to oxygen saturation levels between 90% and 100%, a range considered normal and clinically adequate. In this portion of the curve, even significant increases or decreases in PaO₂ result in only minor changes in SpO₂—indicating hemoglobin is nearly fully saturated and oxygen delivery to tissues is sufficient.

As PaO₂ begins to drop below 80 mmHg, the curve enters its steep middle section. Here, even small reductions in PaO₂ lead to marked decreases in oxygen saturation. Clinically, this is a vulnerable range—patients may appear stable until they reach this tipping point, after which oxygenation can decline rapidly and significantly.

Once PaO₂ falls below 60 mmHg, the curve flattens again, but this time at a dangerously low saturation level. In this lower portion of the curve, hemoglobin's ability to bind oxygen is significantly impaired, and further drops in PaO₂ result in minimal gains or stability in saturation. This is a critical threshold: oxygen delivery to tissues is compromised, and the risk of hypoxia becomes imminent.

Because of this physiological limitation, no physical or occupational therapy interventions should be initiated if the PaO₂ is below 60 mmHg. At this point, the curve indicates there is insufficient oxygen availability to safely support exertion or therapeutic activity. Clinical stabilization is the priority.

However, once PaO₂ reaches or exceeds 60 mmHg, the curve starts to rise more gradually. Although not yet in the optimal zone, this inflection point marks the beginning of a safer range. As such, a PaO₂ of 60 mmHg or higher is generally considered adequate for initiating or resuming therapy, as saturation levels begin to respond more predictably to increases in oxygen pressure.

Potassium

Potassium is one of our critical lab values because plasma potassium concentration directly influences neuromuscular irritability. Both elevated and decreased potassium levels can interfere with skeletal muscle contraction and—more importantly—cardiac conductivity.

Normal and Critical Ranges

• Normal values (Merck Manual): 3.5–5.0 mEq/L
• Normal values (APTA reference): 3.7–5.1 mEq/L
• Hyperkalemia: >5.5 mEq/L
• Hypokalemia: <3.5 mEq/L
• Critical thresholds (Henry Ford guidelines): <3.0 or >6.0 mEq/L

At Henry Ford, patients with potassium levels below 3.0 or above 6.0 mEq/L typically do not receive routine PT or OT interventions due to the risk of serious adverse events. Exceptions may be made on a case-by-case basis, but always with interprofessional collaboration and clear documentation.

For potassium values that fall into the borderline (yellow) zone—just outside the normal range but not in the critical range—we proceed with caution. Vital signs are closely monitored, and therapists assess for any signs of cardiac instability or muscle dysfunction.

Clinical Signs of Potassium Imbalance

When potassium is elevated (trending >5.5):

• Muscle weakness or flaccid paralysis

• Muscle tenderness

• Paresthesias

• Dysrhythmias

• Bradycardia

When potassium is low (trending <3.5, especially <2.5):

• Extreme fatigue or weakness

• Leg cramps

• Hypotension

• Paresthesias

• Dysrhythmias

APTA Recommendations

According to the APTA Acute Care resource manual:

For potassium >5.0 mEq/L, there is an increased risk for cardiac events; therapy should proceed cautiously.

For potassium <2.5 mEq/L, the risk of life-threatening dysrhythmias and acute cardiac events is high.

Therapists should:

• Collaborate with the interprofessional team in the presence of critical hypokalemia.
• Assess and monitor for an acute decline in muscle strength and performance that occurs in an ascending pattern and may progress to flaccid paralysis.
• Monitor cardiac rhythm, vital signs, and symptoms closely, considering possible decreased activity tolerance.
• Use a symptom-based approach when determining appropriateness for activity.

Clinical Decision-Making at Henry Ford: Potassium Protocol

At Henry Ford, our potassium guidelines have remained consistent over the years. We define critical cutoffs as values:

• Less than 3.0 mEq/L
• Greater than 6.0 mEq/L

Patients with potassium levels in these ranges typically do not receive routine physical or occupational therapy that day due to the associated cardiac risks.

We categorize potassium values into three decision zones:

• Green zone (3.5–5.0 mEq/L): Normal range — proceed with routine therapy
• Yellow zone (3.1–3.4 or 5.1–5.9 mEq/L): Caution — monitor vital signs closely for abnormal responses
• Red zone (<3.0 or >6.0 mEq/L): Critical — generally hold therapy unless medically cleared

There are situations where exceptions are made, but always with interprofessional collaboration. For instance, if a patient’s potassium is 2.7 mEq/L, but they are discharge pending and have already received potassium replacement, a physician may approve treatment with close monitoring.

Decisions must be grounded in clinical reasoning, clear communication with the care team, and close observation of vital signs and cardiac status during treatment.

Lastly, it’s important to remember that potassium is primarily an intracellular ion, regulated by renal excretion. This means plasma levels can be significantly influenced by kidney function, medications, and acute illness—factors that must be considered during your clinical assessment.

EBP-Potassium 

I always like to incorporate a bit of evidence when discussing lab values, especially when it supports our clinical decision-making. A while back, we conducted an internal study at Henry Ford focusing on potassium levels and patient response to therapy.

We reviewed data from 380 patients. Among those with normal potassium levels—defined as 3.5 to 5.0 mEq/L—15% experienced adverse reactions, such as dizziness or other symptoms that required us to modify the therapy session. In 3% of those cases, we had to terminate the session altogether.

Interestingly, patients with abnormal (yellow zone) potassium levels—defined as 3.1 to 3.4 or 5.1 to 5.9 mEq/L—had a similar rate of minor adverse reactions (16%), including symptoms like lightheadedness or the need to rest. However, none of those sessions required termination.

These findings helped validate our current approach to the yellow range guidelines. We may proceed with therapy in those ranges, but with increased vigilance, including close monitoring of vitals and patient response throughout the session.

That said, clinical context always matters. If a patient is undergoing a cardiac workup, you’ll want to pause and check the chart for additional information. For instance, if troponins are being collected, or other signs point to ongoing cardiac evaluation, we take extra precautions. In those cases, we ensure all labs are reviewed and within acceptable limits, and we closely monitor pre-, mid-, and post-treatment vitals.

And as always, if a patient displays any signs or symptoms of poor tolerance, particularly when they fall in the abnormal but not critical range, we follow our standard termination criteria:

• Dizziness not resolved/improved within 60 seconds of being upright
• Increase in the patient’s heart rate of 30 bpm over baseline, or Bradycardia, or arrhythmia
• Change in the patient’s systolic blood pressure of 30 mm Hg or a change in the diastolic blood pressure of 10 mm Hg or orthostatic hypotension
• Nausea/Vomiting
• Paresthesia
• Anginal pain 

This evidence-informed approach helps us balance safety with patient-centered care, even when lab values fall into gray zones.

Sodium 

Many hospitals monitor sodium levels, and some therapists do as well. While sodium isn’t always treated as a critical lab value, it can still provide useful insight into how a patient may participate in therapy. It’s not always a red flag—but it may be a yellow light, especially in the presence of mentation changes.

Like potassium, sodium plays a key role in cell membrane potential and supports neuromuscular, renal, and adrenal function. It also serves as a helpful indicator of the patient’s hydration status.

What’s most relevant to us as therapists is that abnormal sodium levels can impact cognition, as the brain is particularly sensitive to sodium fluctuations. This makes it an important value to watch when assessing cognitive readiness, safety, and participation in therapy.

Normal Values

Normal sodium range: 134–142 mEq/L 

Although elevated sodium (hypernatremia) is relatively rare, it occurs most often in the context of dehydration or inadequate water intake. For example, a patient who has been in a coma or cannot hydrate themselves may show elevated sodium levels. Less common causes might also include certain medications or endocrine disorders.

In addition to those possibilities of elevated Sodium, the following are also reasons for increases in sodium: 

• Dehydration (from excessive sweating, severe vomiting, or diarrhea)
• Polyuria (diabetes mellitus, diabetes insipidus)
• Hyperaldosteronism
• Impaired renal function
• Drugs: steroids, licorice, oral contraceptives. 

You're more likely, however, to encounter patients with low sodium levels (hyponatremia). This may occur in:

• Decreased food intake
• Increased water intake/Overhydration (e.g., aggressive IV fluid replacement)
• Diuretic therapies
• Burns
• Chronic Renal Failure
• Diarrhea
• Failure to thrive
• Use of certain medications, such as insulin, ethanol, propranolol, and other oral hypoglycemic agents 

APTA Acute Care Clinical Practice Guidelines: Sodium (Na⁺)

Sodium Trending Up

• >155 mEq/L
• May cause impaired cognitive status
• Initiate seizure precautions for patients with a relevant medical history

Sodium Trending Down

• <130 mEq/L
• May also result in impaired cognitive function
• Monitor vital signs closely due to the increased risk of orthostatic hypotension.

Clinical Implications

Both elevated and decreased sodium levels can impair cognition. As therapists, we often evaluate how far patients are from their cognitive baseline, especially when determining whether they’ll be safe to return home or participate effectively in rehabilitation.

In some cases, a temporary cognitive decline may be attributed to abnormal sodium, and cognition may improve once the sodium is corrected. That’s why it’s important not just to consider the current function, but also what’s reversible.

If a patient's cognitive impairment is so significant that they are unable to follow directions, engage safely, or participate meaningfully in therapy, holding or deferring therapy may be appropriate, especially if sodium imbalance is suspected or confirmed as the cause.

Glucose

Glucose is a commonly monitored lab value that reflects the blood sugar level at the time the sample is obtained. There are two primary ways glucose may be assessed in the hospital setting:

1. Laboratory blood draw – Glucose is measured as part of a diagnostic lab panel, providing a more controlled and standardized result.
2. Point-of-care (POC) testing – Often performed by nursing staff using a fingerstick or glucometer. This method gives a real-time snapshot of the patient's current blood glucose level.

Normal Glucose Ranges

Common reference range: 80–120 mg/dL

Some sources report a slightly narrower range: 70–100 mg/dL

The exact reference range may vary slightly by institution, but both are considered within normal limits for fasting blood glucose in a stable adult.

Causes of Altered Blood Glucose Levels

Glucose Increased (Hyperglycemia) – Trending Up.  May be seen in the following conditions or scenarios:

• Diabetes mellitus
• Cushing syndrome (seen in ~10–15% of cases)
• Chronic pancreatitis (~30% of cases)
• Sepsis
• Brain tumors
• Following a meal
• After IV glucose administration
• Medications: Corticosteroids, Estrogen, Thiazide diuretics

Glucose Decreased (Hypoglycemia) – Trending Down. May be caused by:

• Excess insulin (endogenous or exogenous)
• Brain damage
• Pituitary deficiency
• Addison’s disease
• Malignancies
• Adrenocortical carcinoma
• Stomach cancer
• Fibrosarcoma
• Medications: Insulin, Ethanol, Propranolol, Sulfonylureas, and other oral hypoglycemic agents

APTA ACCPT Guidelines: Glucose

Glucose Trending Up >200 mg/dL

• May indicate diabetic ketoacidosis (DKA)
• DKA can cause severe fatigue and metabolic instability
• Use a symptom-based approach to determine appropriateness for activity
• Monitor for signs of intolerance during mobilization.

Glucose Trending Down <70 mg/dL

• May result in: Lethargy, irritability, shaking, loss of consciousness
• May not tolerate therapy until glucose increased 

Henry Ford Glucose Guidelines

At Henry Ford, our guidelines for therapy in the context of abnormal blood glucose are informed by evidence and interprofessional collaboration. Glucose levels—whether too low or too high—can significantly affect safety, endurance, and cognitive status during therapy.

Glucose <70 mg/dL. Patients with glucose levels below 70 mg/dL will not receive routine OT or PT.

This value is consistent with APTA recommendations and reflects the threshold for hypoglycemia, which can result in:

• Lethargy
• Irritability
• Confusion
• Dizziness or shaking
• Loss of consciousness

If the blood draw was earlier in the day, consider asking the nurse to recheck the patient’s glucose using a point-of-care glucometer.n This may allow therapy to proceed safely later in the day, avoiding unnecessary deferral if the glucose level has normalized.

Now, this is one where we used to have a hard stop. If it was 300, you would not see the patient. Now it's a conversation with the physician. Depending on where that patient is in their illness, we may decide to either hold or to see that patient while monitoring their vitals and for signs and symptoms of intolerance. One of the reasons we chose 300 as our guideline is that that's the indicator our physicians have agreed upon that is severe hyperglycemia.

If the patient has a glucose greater than 300 and ketones are present, then exercise can cause that diabetic ketoacidosis and the cells lack energy source to function. So you always want to consider what is it you're going to be doing with that patient. You may not be doing like a lot of exercise in the acute care setting. It may just be their basic level of activity to see if they're safe to go home. So you do want to decide what is it that you are doing with the patient to make a decision whether that number is a hard stop or not.

Glucose >300 mg/dL. Historically, this value was treated as a hard stop for therapy. Today, our approach is more nuanced. Patients with glucose levels over 300 mg/dL are not automatically deferred—rather, this becomes a clinical discussion with the physician. Decisions are made based on:

• Current trends in glucose readings
• The patient’s overall clinical status
• Their stage of illness or recovery
• The goals and intensity of the planned session

For example, therapy may proceed for discharge readiness or light activity, while more strenuous interventions may be deferred.

Why 300? The 300 mg/dL threshold reflects the level at which our physicians consider severe hyperglycemia to pose increased metabolic risk. Specifically:

• If glucose is >300 mg/dL and ketones are present, the patient is at risk of developing or worsening diabetic ketoacidosis (DKA).
• In this state, the body lacks adequate glucose metabolism, and exercise may worsen the energy deficit, leading to further metabolic instability.
• Patients may have severe fatigue and in need of insulin

Clinical Examples: Glucose Levels and Therapy Decision-Making

Case 1: Hypoglycemia During Morning ADLs. A 54-year-old patient was admitted with dehydration and is currently undergoing chemotherapy for stomach cancer. The patient does not have a history of diabetes. At 7:00 a.m., their blood glucose was recorded at 65 mg/dL. Breakfast was scheduled for 8:00 a.m. At 7:30 a.m., the occupational therapist (OT) initiated morning ADLs, deciding to proceed with the session since breakfast was imminent. However, during the session, while the patient was performing ADLs at the bathroom sink, they became confused and reported dizziness and blurred vision.

The nurse was immediately notified, and a follow-up point-of-care glucose reading revealed a drop to 45 mg/dL.

This episode likely occurred because of a pre-breakfast state compounded by the energy expenditure of even light activity, which was sufficient to further lower glucose levels in a vulnerable patient receiving chemotherapy. This scenario highlights the importance of timing therapy in relation to meals for patients at risk of hypoglycemia, even when the activity appears low-level.

Case 2: Hyperglycemia in an Uncontrolled Diabetic. A 43-year-old female was admitted with uncontrolled diabetes, with blood glucose values ranging from 350 to 600 mg/dL over the past several days. Despite persistent hyperglycemia, the patient was medically cleared for discharge, and a referral for physical therapy evaluation was placed even though the patient's glucose level was greater than 300.

The physical therapist proceeded with a discharge readiness assessment, limiting the session to basic mobility and safety tasks without introducing additional exercise or exertion. Vital signs were monitored throughout, and the patient’s fatigue and response to activity were carefully documented.

In this case, although the patient’s glucose level was significantly elevated, the therapy session was appropriate because:

• The intervention was limited to essential discharge assessment,
• The patient's response was stable, and
• The care team was actively managing glycemic control.

These two examples illustrate how timing, context, and patient condition critically affect therapy decisions when dealing with abnormal glucose levels. Hypoglycemia can develop rapidly, especially in patients without diabetes who are fasting or undergoing treatments like chemotherapy. Conversely, stable patients with hyperglycemia may still safely engage in carefully tailored therapy, especially when the goal is discharge planning.

Always use a symptom-based approach, closely monitor vitals and patient response, and consider factors like meal timing, medication effects, and overall clinical picture when making therapy decisions.

White Blood Cells

Next, let’s look at white blood cells (WBCs)—a lab value that, while not typically associated with a strict critical threshold, is still a valuable indicator of disease and a patient's readiness for therapy.

WBCs play a key role in the body’s immune response and are elevated in the presence of infection, inflammation, or allergic reactions. They are most often used to help identify underlying infectious processes.

Normal Ranges and Units

Traditional unit: 4,500 to 1,060,000 cells per cubic millimeter (mm³)

Occasionally reported as: 5.0 to 10.0 x 10⁹/L (liters)

Causes of Elevated or Decreased WBCs

There are many reasons why you may see white blood cells trending up.  Those include: 

• Parasitic infections
• Bacterial infections
• Inflammation trending
• Tissue injury/necrosis
• Leukemia/Lymphoma
• Allergic reactions
• Hypersensitivity reactions
• Stress
• Smoking
• Corticosteroids 

The reasons WBC may decrease include: 

• Viral infections
• Chemotherapy/Radiation
• Bone marrow transplant
• Immune compromise
• Neutropenia
• Myelodysplasia
• Alcoholism 

APTA AACPT Guidelines: White Blood Cells

Trending upward: > 11.0 109/L or 11,000 cells/mm^3.

• Fever, lethargy, dizziness, painful joints
• Symptom-based approach to appropriateness; consider timing of session due to early morning low level or late afternoon high peak

Trending downward: <4.0 109/L Leukopenia.

• Anemia, weakness, fatigue, headache, SOB, fever
• Symptom-based approach to appropriateness, especially in the presence of fever

Trending downward: <1.5 109/L Neutropenia.

• Low-grade fever, skin abscesses, sore mouth, symptoms of pneumonia 
• Symptom-based approach to appropriateness, especially in the presence of fever 

Clinical Implications

The APTA Acute Care guidelines include considerations for WBCs, particularly in immunocompromised patients. Interpretation depends on trends, symptoms, and context.

Elevated WBCs may be seen in patients who are febrile, fatigued, or showing general signs of systemic illness. These patients may tolerate therapy, but consider the overall clinical picture.

Decreased WBCs, especially in neutropenic patients, warrant more caution:

• Use a symptom-based approach to determine appropriateness for therapy.
• Consider the timing of treatment and the type of intervention.
• Patients with neutropenia should wear a mask, and clinicians should minimize infection risk.
• Be aware of associated symptoms: anemia, weakness, fatigue, shortness of breath, and general malaise.

For patients with very low WBC counts, especially those with neutropenia, be alert for:

• Sore mouth or oral ulcers
• Skin abscesses
• Pneumonia symptoms
• Generalized inflammation or signs of infection

These individuals may be at significantly higher risk for infection and systemic complications, and therapy may need to be modified or deferred based on symptoms and consultation with the care team.

Platelets

Platelets are most frequently considered in patients with oncology diagnoses, but they can be relevant across a variety of patient populations. Their primary function is to initiate the clotting cascade and form plugs at sites of vascular injury, helping to prevent excessive bleeding.

Normal Values

• 150,000 to 450,000/µL (often expressed as 150–450 × 10³/µL or "per microliter")
• Also reported as 140-400 k/uL 

Causes of Abnormal Platelet Counts

Elevated Platelets (Thrombocytosis):

• Commonly associated with myeloproliferative disorders (polycythemia vera, chronic myeloid leukemia, essential thrombocythemia, myelofibrosis)
• It can also occur due to acute blood loss, which alters the ratio of circulating blood cells
• May increase the risk of thrombosis or clot formation
• Tissue Injury 
• Infection
• Iron deficiency
• Some malignancies

Decreased Platelets (Thrombocytopenia):

• Leukemia/lymphoma 
• Other cancers
• Chemotherapy
• Bone marrow suppression or replacement/infiltration
• Post bone marrow transplant
• Drugs, Alcohol 
• Myelodysplasia
• Infection (HIV)

APTA AACPT Guidelines: Platelets

Trending Upward: >450 k/uL. May present with:

• Weakness
• Headache
• Dizziness
• Chest pain
• Tingling in the hands or feet

These symptoms are often due to increased platelet volume and associated blood viscosity. Use a symptom-based approach to determine appropriateness for therapy. Monitor for cardiovascular or neurologic signs that may indicate intolerance.

Trending Downward: <150 k/uL. May exhibit:

• Fatigue
• Jaundice
• Splenomegaly
• Increased bleeding risk

These patients are often more fragile, particularly those with oncology or hematologic conditions. Again, rely on a symptom-based approach, and consider the context—such as recent transfusions or active bleeding concerns.

Severely Decreased: <20 k/uL. Presents a significant fall risk due to the potential for spontaneous hemorrhage, including internal bleeding. Even minor trauma could lead to severe consequences. Therapy is not automatically contraindicated, but interventions should be carefully modified, and close collaboration with the medical team is essential.

Henry Ford Guidelines: Platelets

At Henry Ford, we follow detailed guidelines provided by our oncology and hematology teams to determine safe activity levels based on platelet count thresholds. These guidelines help inform physical and occupational therapy interventions, especially for patients undergoing chemotherapy or experiencing bone marrow suppression.

>50,000k/µL- Activity as tolerated. Includes ambulation, use of a stationary bike, and moderate resistance strength training

20k - 50 k/uL - can do ambulation and light resistance training

5- 20 k/uL - can do active ROM, ambulation in room, light daily activities.

< 5 k/uL for less than 1 week - can do transfers. 

< 5 k/uL for greater than 1 week - Modified therapy permitted using the same precautions as the 5,000–20,000 range.

• Based on a risk–benefit analysis, prolonged immobility may present greater harm than minimal activity.

• Light in-room movement and ADLs may be beneficial in such cases, with extreme caution.

Muscular and Cardiac Markers

You may not encounter these values in every patient chart, but if you do, they should prompt closer attention. These findings can be considered soft red flags—subtle indicators that something may warrant further investigation. If muscular or cardiac biomarkers are being collected, it’s likely that the care team has a clinical concern driving that decision. In such cases, it is important to pause and dig deeper: review the context, examine relevant clinical notes or lab trends, and determine the underlying rationale. These markers aren’t ordered arbitrarily; they often reflect suspected or ongoing pathology that could impact clinical decision-making, activity tolerance, or safety during intervention.

Creatine Kinase (CK) 

The first lab value to discuss is a musculoskeletal marker known as creatinine kinase (CK), also referred to as CPK. This enzyme is released into the bloodstream whenever there is muscle tissue damage anywhere in the body. At the time of blood sample collection, laboratory scientists measure the amount of this enzyme present to assess the extent of muscle injury.

Historically, CK was the primary biomarker used to detect cardiac muscle damage, such as in a heart attack. However, the clinical focus has since shifted to troponins, which are now the preferred marker for evaluating cardiac injury. Still, CK remains clinically relevant because it is found in three types of muscle tissue:

• CPK-MB: Released from cardiac muscle, especially following myocardial infarction (MI) or other cardiac injuries.
• CPK-MM: Released from skeletal muscle, often due to trauma, muscular dystrophy, or more commonly, rhabdomyolysis (seen in patients who have been immobilized for extended periods).
• CPK-BB: Found in brain tissue, typically elevated after severe brain injury or shock.

Normal Values

• General reference range: 30–170 U/L
• Men: 38–174 U/L
• Women: 26–140 U/L

Of the total CK in circulation, approximately 96% should be the MM (skeletal muscle) isoenzyme. Cardiac-specific CK-MB should account for no more than 0–5%. When CK-MB exceeds this proportion, cardiac involvement may be indicated.

Timing and Kinetics

CK levels typically rise 4–6 hours after muscle injury, peak around 12–24 hours, and normalize within 48–72 hours. Because of this, if CK is being monitored, it’s often done serially—initially upon admission, then repeated at 4-hour intervals, and possibly again at 12 or 24 hours to track the trend.

Clinical Considerations

Patients with elevated CK may present with:

• Muscle weakness or pain
• Dark, tea-colored urine, a hallmark of muscle breakdown (particularly notable in Foley bags)

Importantly, certain medical interventions can elevate CK even in the absence of pathology:

• Cardiac surgery
• CPR
• Defibrillation

These procedures inherently cause muscle trauma, which elevates CK levels, though not necessarily indicating an acute cardiac event.

At Henry Ford, routine cardiac evaluation typically relies on troponins, not CK. When CK or CPK is drawn, it usually investigates skeletal muscle damage rather than heart-related concerns.

Clinical Example

A 77-year-old woman was found at home two days after sustaining a fall. No loss of consciousness was reported. Imaging revealed a right wrist fracture on X-ray, and CT of the head was negative for acute findings. On chart review, laboratory data show a creatine phosphokinase (CPK) level of 400 U/L, with the CPK-MB isoenzyme measuring 15 U/L, accounting for 3.8% of total CPK—a proportion not suggestive of primary cardiac injury. This interpretation is further supported by stable vital signs and negative troponins.

She was given a diagnosis of rhabdomyolysis, attributed to prolonged immobilization after the fall. Rhabdomyolysis indicates skeletal muscle breakdown, often due to pressure-related ischemia, and warrants ongoing monitoring for associated systemic complications.

Clinical Considerations and Red Flag Indicators:

• Rhabdomyolysis may lead to renal impairment, electrolyte disturbances, and in some cases, compartment syndrome.

• Be alert for signs of reduced distal pulses, sensory or motor changes, or disproportionate pain, especially in the extremities, as these may indicate emerging compartment syndrome.

• Though the CPK level is only modestly elevated, the presence of rhabdomyolysis requires clinical vigilance, especially during mobilization and rehabilitation planning.

• Use a symptom-based approach and consider deferring activity or therapy if systemic signs (e.g., muscle pain, weakness, dark urine, swelling) worsen.

Troponin

Troponin is one of the most critical lab values to assess when evaluating a patient for physical or occupational therapy. Its presence on a lab panel should immediately signal a possible cardiac workup, prompting careful review of timing, trends, and accompanying clinical data.

Troponins are regulatory proteins found in striated muscle cells, and they exist in three isoforms:

• Two are specific to cardiac muscle: Troponin T (TnT or cTnT) and Troponin I (TnI or cTnI)

• One originates from skeletal muscle

The cardiac-specific isoforms—TnT/cTnT and TnI/cTnI—are only expressed by cardiac tissue and are the only two tested during suspected ischemia or infarction. When cardiac muscle cells undergo necrosis, troponin proteins are released into circulation. This is the basis for using cardiac troponin levels as a biomarker for myocardial damage.

At our institution, we measure high-sensitivity cardiac troponins (hsTnT) to detect even minor myocardial injury. Other facilities may use different troponin assays, so it’s important to verify which test is being used.

Troponin Normal Reference Ranges

• Standard troponin (Troponin T): less than 0.1 ng/mL
• Troponin I: less than 0.03 ng/mL
• High-sensitivity cardiac troponin:
  • Women: less than 14 ng/L
  • Men: less than 22 ng/L

In most electronic medical records, the reference range will be included with the lab result. At our institution, we consider less than 18 ng/L as normal for high-sensitivity cardiac troponin.

Troponin levels begin to rise approximately 8 hours after cardiac muscle injury, peak around 12–16 hours, and may take up to a week to return to baseline. As a result, labs are often ordered in sets—typically "troponin x3"—drawn every 8 hours to observe trends.

Henry Ford Clinical Guidelines for Troponin

• <18 ng/L: Considered negative for myocardial damage; therapy may proceed.
• 18–100 ng/L: Indeterminate. Review the chart for documentation on why the troponin was ordered. If cardiac involvement is ruled out, therapy can proceed.
• Greater than 100: Indicates myocardial damage.
  • If this is a new peak, therapy is held. 
  • Therapy may begin 24 hours after the most recent peak, provided the patient is hemodynamically stable.  
  • Always look for the trend since a NEW peak indicates further cardiac damage. 

Interpreting Trends

The key clinical priority is trend interpretation. Even if a value is >100 ng/L, the patient may be appropriate for treatment after the 24-hour window if it is past the peak and on a downward trajectory. Conversely, if a new peak appears, treatment should be deferred, and the clock should be reset.

Troponin Leak: Elevation Without Infarction

It is also important to be aware of a phenomenon known as a troponin leak. This occurs when cardiac troponin levels are elevated without evidence of an acute coronary syndrome or myocardial infarction. Although the lab value may appear concerning, the elevation alone does not contraindicate physical or occupational therapy. Clinical decision-making should be guided by the overall presentation and in consultation with the medical team.

Common causes of troponin leaks include:

• Sepsis or systemic shock

• Acute pulmonary embolism or pulmonary hypertension

• Acute pericarditis or myocarditis

• Renal failure

• Defibrillation, CPR, or recent cardiac surgery

• Stroke or subarachnoid hemorrhage 

• COPD

• False-Positive Troponin 

• Hypertensive Emergency

Clinical Example (see charts in your handout)

Patient: 82-year-old with chest pain
PT Consult Ordered: July 23 at 12:00 p.m.

Vital Signs:

• BP: 168/72 mmHg

• HR: 92–108 bpm

• SpO₂: 94% on 4L O₂

Troponin Timeline:

• July 22, 3:00 p.m. – 200 ng/L

• July 22, 7:00 p.m. – 6400 ng/L (Peak 1)

• July 22, 11:00 p.m. – 4500 ng/L

• July 23, 9:00 a.m. – 10,120 ng/L (new peak, Peak 2)

• July 23, 3:00 p.m. – 9300 ng/L

• July 23, 11:00 p.m. – 8500 ng/L

• July 25, 8:00 a.m. – 4230 ng/L

• July 27, 8:00 a.m. – 40 ng/L. (greater than 1 week to reabsorb the enzyme)

Decision-making:  The new peak occurred at 7:00 a.m. on July 23. According to Henry Ford’s protocol, the patient can be treated no earlier than 7:00 a.m. on July 24, assuming vital signs remain stable. Even if troponins are still above 100 ng/L, therapy may proceed once 24 hours have passed since the peak.

B-Type Natriuretic Peptide (BNP) 

While it’s not considered a critical value in clinical decision-making for rehab, it’s an important biomarker that provides insight into a patient’s cardiac function, specifically in relation to heart failure. BNP is a hormone secreted by the ventricles in response to increased pressure and volume overload. Elevated BNP levels are commonly associated with worsening heart failure.

Although BNP itself is not a reason to defer treatment, it serves as a predictive marker. An elevated BNP may indicate that the patient is likely to have decreased activity tolerance or may experience rapid physiological decompensation, which can influence how you plan or modify your session.

You might also consider reviewing BNP levels in conjunction with troponins. If troponin is slightly elevated and BNP is also high, it may suggest the patient is experiencing chronic or congestive heart failure, rather than an acute myocardial event. In such cases, the elevated troponin could be secondary to prolonged cardiac strain, rather than acute infarction.

Coagulation Assays

This next category of lab values—coagulation tests—may not appear routinely in every patient's chart. However, they often surface when there's a clinical concern, such as a suspected deep vein thrombosis (DVT) or when a patient is receiving anticoagulation therapy.

These labs assess the viscosity of the blood—in other words, how "thick" or "thin" the blood is—and evaluate the bleeding and clotting time. Rather than counting specific cells, as with hemoglobin or white blood cells, these tests measure the time it takes for blood to clot. Different tests may be ordered depending on the patient’s condition or medication regimen.

The most commonly used coagulation assays include:

• PTT (Partial Thromboplastin Time)

• PT (Prothrombin Time)

• INR (International Normalized Ratio)

• Anti-Factor Xa Assay

We'll explore each of these in detail shortly.

Why These Values Matter

When any of these values are elevated, it indicates that the blood is taking longer to clot, suggesting an increased bleeding tendency. The higher the result, the longer it took for clotting to occur.

In these situations, patients may:

• Bruise more easily (be cautious with blood pressure cuffs and other medical devices)

• Experience oozing from wounds or mucosal bleeding

• Have an elevated risk of internal or intracranial bleeding, especially if they fall

This has important implications for therapy. In such cases, you should:

• Implement fall prevention strategies and reinforce fall risk education

• Use extra care during mobility tasks—a fall could have catastrophic consequences

• Apply prolonged pressure to any site of bleeding

• Inspect the skin for signs of bleeding, such as petechiae or unexplained bruising

• Monitor neurological status closely, watching for subtle changes that might indicate intracranial hemorrhage

• Collaborate with the interprofessional team to determine if the current values are within therapeutic range and whether any modifications to treatment intensity or exercise prescription are warranted

Remember, not every elevation is a reason to defer care outright. However, values outside the expected therapeutic range should trigger careful clinical consideration and interprofessional communication before proceeding with intervention.

PTT = Partial Thromboplastin Time

The first test to review is partial thromboplastin time, or PTT. This lab value measures an intrinsic clotting factor and is primarily used to monitor the effectiveness of heparin therapy. It is also helpful in screening for certain bleeding disorders. Elevated PTT levels are common after thrombolytic or heparin infusions, as these medications prolong the time required for blood to clot—thereby increasing the risk of bleeding.

For example, if a patient has been diagnosed with a deep vein thrombosis (DVT) and started on heparin, the PTT test helps determine whether the dosage is therapeutic or excessive.

In individuals who are not taking anticoagulants, the normal clotting time is approximately 21 to 35 seconds. For patients on heparin therapy, the therapeutic range increases to about 60 to 109 seconds—roughly two to three times the normal value.

At our institution, if a patient's PTT exceeds 200 seconds, we consider this a critical value due to the increased risk of bleeding. In such cases, physical and occupational therapy are not initiated automatically. Instead, we consult with the patient’s medical team to determine the appropriate activity level. Based on the clinical decision, we may either hold treatment or proceed with added precautions. All physician recommendations are documented in the patient’s chart.

PT=Prothrombin

Prothrombin Time (PT) is a laboratory test that measures how long it takes blood to clot, using the same principles as the Partial Thromboplastin Time (PTT) test. However, PT specifically evaluates the effectiveness of oral anticoagulant medications such as Coumadin (warfarin).

This test is often ordered for patients transitioning to home who are being started on or maintained with oral anticoagulation therapy. It is especially useful for monitoring those without an acute deep vein thrombosis (DVT), but who require long-term clotting management.

The normal PT range for individuals not on anticoagulation therapy is approximately 11 to 13 seconds. For those taking Coumadin or warfarin, the therapeutic goal is for the blood to clot in about two to three times that normal range—typically around 25 seconds. This extended clotting time ensures that the medication is effectively thinning the blood without causing excessive risk of bleeding.

INR = International Normalized Ratio

The INR, or International Normalized Ratio, is a lab value you’ll frequently see in the patient chart. Often, you’ll notice that discharge is delayed until the INR reaches a therapeutic range. While the full details of coagulation management may go beyond the scope of your role, it's important to understand why this number matters.

A therapeutic INR varies depending on the patient's diagnosis and risk factors. In clinical practice, we closely monitor this value because it reflects the effectiveness of anticoagulation therapy, and more importantly, it helps guide safe clinical decisions.

For example, if a patient’s INR is greater than 6, physical and occupational therapy are generally held. However, in such cases, we always consult with the physician’s team to determine whether it is appropriate to proceed with treatment. This decision involves a careful risk-versus-benefit analysis and must be clearly documented.

INR Ranges and Clinical Relevance

Normal INR:

• 0.8 – 1.2

Common Therapeutic Ranges:

• Stroke prophylaxis: 2.0 – 2.5

• Patients with venous thromboembolism (VTE), pulmonary embolism (PE), or atrial fibrillation: 2.0 – 3.0

• Patients at higher clotting risk (e.g., prosthetic heart valves): 2.5 – 3.5

• Patients with lupus anticoagulant: 3.0 – 3.5

• INR > 3.6 may indicate elevated bleeding risk

• INR > 6.0 requires physician consultation before initiating PT/OT

Therapists must document physician recommendations clearly in the medical record, especially in patients with supratherapeutic INR levels, due to increased bleeding risk.

Anti-Factor Xa Assay

The last lab value to be aware of is the anti-factor Xa assay, which is used to monitor the effectiveness of heparin-based anticoagulants, particularly Lovenox.

Lovenox, also known as enoxaparin, is classified as a low molecular weight heparin (LMWH). While we don’t focus on specific medications in this course, Lovenox is an important exception. You’ll frequently encounter it in patients recovering from total joint replacements or other elective surgeries. It’s often prescribed prophylactically to reduce the risk of blood clots during the postoperative period.

Therapeutic and Prophylactic Ranges

You’ll see anti-factor Xa values expressed in international units per milliliter (IU/mL). The therapeutic and prophylactic ranges differ depending on whether the patient is receiving LMWH or unfractionated heparin (UH):

Therapeutic ranges

• LMWH (e.g., Lovenox): 0.5 – 1.2 IU/mL

• UH: 0.3 – 0.7 IU/mL

Prophylactic ranges

• LMWH: 0.25 – 0.5 IU/mL

• UH: 0.1 – 0.4 IU/mL

You’ll often encounter these values in the context of lab monitoring, but there’s no need to memorize the specific numbers. Instead, focus on understanding when a patient might be at increased risk for bleeding or clotting and how that might impact your clinical decision-making. As always, when in doubt, confer with the medical team.

Lovenox

Although there isn’t a routine lab test exclusively associated with Lovenox, the anti-factor Xa assay may be ordered when more detailed monitoring is needed. However, what’s most important for you to know is this: if a patient is on Lovenox and has been diagnosed with a deep vein thrombosis (DVT), they must receive a therapeutic dose before physical or occupational therapy can begin. This means the patient will need an additional dose of Lovenox after diagnosis to ensure that the blood has been sufficiently anticoagulated. The goal is to reduce the risk that movement could dislodge the clot, potentially leading to an embolism.

APTA AACPT Guidelines: Known DVT

The guidelines for anticoagulation management are summarized in a clinical decision algorithm published by the APTA’s Acute Care Academy. Although the visual reference may be small and difficult to read in your handout, the key takeaway is clear: for each type of anticoagulant medication, there are corresponding lab values that may be monitored, and based on those, we determine whether or not to proceed with therapy.

These recommendations align closely with our institutional guidelines at Henry Ford Hospital, which I’ll describe next.

HFH Guidelines related to DVT 

Since 2011, physicians within the Henry Ford Medical Group have determined that the risks associated with delayed mobilization and therapy prior to reaching therapeutic anticoagulation levels outweigh the risks of complications such as clot mobilization or embolism. This shift in philosophy was based on the understanding that extended bedrest carries significant risks of its own—deconditioning, secondary complications, and the potential for additional clot formation.

As a result, patients diagnosed with an acute upper extremity DVT, lower extremity DVT, or pulmonary embolism may be mobilized without restrictions once anticoagulation (such as Heparin or Lovenox) has been started. Importantly, no minimum time interval or required PTT or INR value must be achieved before initiating therapy after anticoagulation has begun.

However, certain precautions remain critical to safe patient care:

• If a DVT or PE is suspected, therapy is deferred until diagnostic testing has been completed. Appropriate diagnostic tools include venous Doppler ultrasound (upper or lower extremity), CT angiography, or a ventilation-perfusion (V/Q) scan.

• If symptoms arise during a session—such as a painful, swollen, or reddened limb, or a positive Homan’s sign—therapy should be paused, the provider notified, and testing ordered to rule out thromboembolism. Therapy should only resume once the condition has been evaluated.

• If a patient is unable to receive anticoagulation due to medical contraindications, but has an inferior vena cava (IVC) filter placed, they may be mobilized without restriction once the filter is in place. The IVC filter helps prevent emboli from reaching critical organs like the lungs or brain.

• For the small number of patients who fall outside standard protocols—either because they cannot be anticoagulated or for other unique clinical reasons—PT/OT must consult with the medical team before proceeding with therapy. Activity should be tailored to individual risk, and medical guidance must be clearly documented.

Regardless of the clinical scenario, therapists must always:

• Document medical recommendations in the patient’s chart

• Monitor and record vital signs during and after treatment

• Describe the patient’s response to mobility or exercise interventions

This patient-centered, risk-aware approach allows clinicians to safely initiate therapy while minimizing harm and promoting early mobilization whenever possible.

Other Lab Values

You might come across several other lab values in the electronic medical record that we won’t cover in detail during this course, but they’re still worth pointing out. These values may not directly influence your decision to treat or modify a therapy session. Still, they can offer helpful insight into a patient’s condition, especially in relation to specific body systems.

Most electronic medical records will highlight abnormal lab values, either by changing the color of the result or marking it in some other noticeable way. Even so, assessing the trend is important rather than focusing on a single out-of-range result. Ask yourself: Is this meaningful to your clinical reasoning? Does it help guide your decision to intervene?

Below are a few examples of values that might not change your immediate treatment plan but are still helpful to understand in the broader clinical context:

Kidney Function: Blood Urea Nitrogen (BUN)

BUN, or blood urea nitrogen, provides insight into kidney function. Elevated BUN levels can suggest declining renal performance, and in some cases may be a sign that the patient is approaching the need for dialysis.

Kidney Function: Serum Creatinine

Serum creatinine is another key marker of renal function, and it may be especially important to monitor in patients with known kidney issues or in cases of sepsis. In the intensive care unit, creatinine levels are frequently used to track whether a patient’s condition is improving or deteriorating.

Acid-Base Disorders: Respiratory and Metabolic Alkalosis or Acidosis

Lab values can also reflect imbalances in the body’s acid-base status. Conditions like respiratory or metabolic alkalosis and acidosis may not require a change in physical therapy intervention, but they can signal underlying physiologic stress or instability that should be acknowledged.

Liver Function: Serum Albumin and Pre-Albumin

Nutritional status often influences liver function tests, including serum albumin and pre-albumin. While low albumin levels may raise concerns, current evidence does not suggest that albumin alone is a standalone red flag that should change your treatment plan. However, it can contribute to a broader picture of the patient’s systemic health.

Electrolyte Panels: Calcium, Chloride, Phosphate, Magnesium

You’ll also notice other electrolyte levels in the chart, such as calcium, chloride, phosphate, and magnesium. We won’t cover these in detail here, but they’re commonly included in comprehensive metabolic panels. They generally don’t influence immediate treatment decisions unless severely abnormal, but they’re part of the overall clinical puzzle.

Quick Reference Guides

There are quick reference guides available to support your clinical decision-making. You’ll find the links to the APTA resource guides in your reference handout, along with a copy of the Henry Ford Rehab Lab Values Manual. I like to review key concepts more than once and in different ways, so I want to highlight again the top lab values I routinely check during my medical record review as a therapist.

The first three lab values I check for every patient are hemoglobin, potassium, and glucose. These are the core values I consider for every patient:

Hemoglobin

This is the first lab I look at for all patients. If a patient’s hemoglobin is below 8 g/dL, I immediately begin thinking about the possible clinical implications. Lower hemoglobin can mean decreased exercise tolerance, increased fatigue, or elevated heart rate. If it drops below 7, I often hold therapy—though I always dig deeper to understand the cause.

Trends are important. For example, if a post-op orthopedic patient had a hemoglobin of 14 yesterday and it drops to 8 today, that’s a significant change. I’d want to consider whether there’s active bleeding and assess the surgical site carefully. On the other hand, if a patient is chronically anemic and regularly lives at a hemoglobin of 7.5 to 8, I may proceed with therapy, monitoring vital signs and activity tolerance closely.

Potassium

Potassium is critical for cardiac function. If the level is below three or above six, I typically hold therapy until it returns to a safer range. Between 3.1 and 5.9, I proceed with caution. I monitor blood pressure and heart rate closely and watch for signs of arrhythmia.

My level of concern also depends on whether the patient is being monitored. On a cardiac floor with telemetry, I may feel more confident seeing a patient with a potassium of 2.9 or 3.4 because I’ll receive alerts if an arrhythmia develops. Without telemetry, I’m more hands-on, checking vitals before, during, and after treatment, and sometimes keeping a pulse oximeter on during the session to watch for changes in heart rate that may signal atrial fibrillation or other rhythm disturbances.

Glucose

Blood glucose is another value I check for every patient. If it’s below 70 mg/dL, I avoid therapy because activity can further lower glucose, increasing the risk of dizziness, fatigue, or even seizures. You may have seen hypoglycemic patients who needed immediate sugar intake to recover.

If the glucose level is above 300, I may hold therapy depending on the patient. A reading over 300 raises concern for the risk of ketoacidosis. However, if the patient is a newly diagnosed diabetic or adjusting insulin, this may be a known trend. In such cases, I may still proceed with therapy but tailor the session to focus on safety for discharge or education.

Platelets

I don't look at platelet counts for every patient, but I pay attention when I see them, especially on oncology units where low platelet counts are more common. If a patient’s platelets are below 20,000, I limit activity to in-room mobility. Below 5,000, I assess how long they’ve been that low and may defer therapy entirely.

For example, if it’s been less than a week with platelets under 5,000, I may step back and allow OT to provide basic ADLs at the bedside or in a chair. If I’m the PT, I may wait to see the patient when their platelet levels recover, especially if the risk of bleeding outweighs the benefit of a short session.

Additional Labs to Watch

These labs don’t always prompt immediate action, but they offer insight into the patient's status and can guide further clinical reasoning:

• Coagulation studies: If PT or PTT values are drawn, consider the type of anticoagulation the patient receives. PT is commonly associated with oral anticoagulants, while PTT corresponds with IV heparin. I’m not necessarily focused on the precise clotting time, but if the PTT is over 200 seconds, I will hold therapy and consult with the physician.

• INR: This is a value I see often in patients with atrial fibrillation, stroke, or clotting disorders. If the INR is above 6, I pause therapy and reach out to the medical team.

• Troponin: This lab is a red flag for potential cardiac events. I don't zone in on every troponin value unless it’s being drawn for a reason. If troponin is below 18 and only one result is pending, I typically proceed with therapy. But if the patient has three troponin values and all are completed—with the peak over 100—I assume a myocardial infarction occurred. In that case, I look at the timing of the peak and ensure it’s been at least 24 hours since the highest result before initiating therapy.

Clinical Cases

Clinical Case #1

Let’s walk through six clinical cases, beginning with Mr. J.  Mr. J was admitted to the nephrology general unit with kidney failure and an exacerbation of gouty arthritis. This morning, he was NPO (nothing by mouth) in preparation for a transesophageal echocardiogram (TEE), which has since been completed. He has not eaten today, except to take his medications within the past hour.

Past Medical History 

His past medical history includes:

• Hypertension

• Diabetes mellitus

• Gout and arthritis

• Prior myocardial infarction (MI)

• Chronic renal failure

From his medication administration record, we see that he recently received:

• Lisinopril (for blood pressure control)

• Insulin on a sliding scale

• Ibuprofen (for joint pain)

These were all administered within the last hour.

Lab Values

• Glucose: 250 mg/dL

• Hematocrit: 42%

• Hemoglobin: 9.9 g/dL

• Potassium: 3.6 mmol/L

• Sodium: 138 mmol/L

Vital Signs This Morning

• Blood pressure has ranged from 145/72 to 179/75

• Current BP: 168/98 (shortly after receiving lisinopril)

• Heart rate: fluctuating between 90–110 bpm

• Oxygen saturation: consistently 99–100% on 2L nasal cannula

Appropriate For Therapy? 

Based on this data, would you consider Mr. J appropriate for therapy intervention?

My interpretation is that he is appropriate to be seen. Although his blood pressure is elevated, it is consistent with his medical history. Given that he just received his antihypertensive medication, I would proceed, but continue to monitor closely for potential changes.

Patient Encounter

Upon entering the room, Mr. J reports feeling dizzy, like he might faint.

So now we ask: What could be contributing to this dizziness?

Several possibilities come to mind:

• Orthostatic hypotension: Following antihypertensive medication

• Hypoglycemia: Blood glucose dropped post-insulin, especially since he hasn’t eaten

• Medication effect: Particularly from lisinopril, which can cause a sudden drop in blood pressure

• Dehydration or dialysis-related fluid shifts:  Relevant to his renal condition

Clinical Response

In this situation, I would immediately monitor:

• Blood pressure

• Heart rate

• Oxygen saturation

If symptoms persist beyond 1–2 minutes, I would lie Mr. J back down and reassess his vitals. Then, I’d communicate my findings to the nurse and the physician, noting any changes in vital signs associated with position changes, especially comparing supine to sitting or standing.

This case is a good example of how reviewing labs and vitals helps guide decisions. Still, real-time patient response remains essential in determining whether it’s safe to proceed with therapy.

Clinical Case #2

Mr. D has been hospitalized for four days following a total shoulder replacement. His post-operative course has been complicated by increased pain, poor oral intake, and swelling in the affected upper extremity.

He began receiving prophylactic Lovenox on post-op day one. However, by post-op day three, he was diagnosed with a left upper extremity deep vein thrombosis (DVT). In response, the care team initiated IV heparin to treat the clot.

Lab Values

• Glucose: previously stable, currently 60mg/dL 

• Hematocrit: stable

• Hemoglobin: started at 11.9 g/dL, now 8/2g/dL

• Potassium: 3.6 mmol/L (tends to run low)

• Sodium: trending low but within range

• White blood cell count: 8500 → 9000 → 8800 (stable)

• Troponins: all values less than 18

• PTT (heparin monitoring): currently 34 seconds

Clinical Interpretation

Let’s start with the glucose. At 60mg/dL, this value falls below the threshold of 70, which means Mr. D is not appropriate for therapy at this time. Activity could cause further drops in glucose, putting him at risk for symptoms such as dizziness, weakness, or even hypoglycemic events.

While his hemoglobin has decreased from 11.9 to 8.2, it remains within an acceptable range for activity, though we’d expect some decreased tolerance and would monitor accordingly.

His PTT is currently 34 seconds, which is below the therapeutic range for heparin. That suggests he may not yet be fully anticoagulated. However, that alone doesn’t rule him out for therapy in all cases—our primary concern in this moment is his low glucose level.

Cardiac Considerations

Given that troponins were drawn, you might be wondering whether Mr. D has had a cardiac event. However, based on repeated troponin values below 18, there no indication of myocardial injury. In other words, we are not concerned about a recent MI at this time.

Clinical Case #3

Mr. Z is a 46-year-old male with morbid obesity and newly diagnosed end-stage renal disease. He is currently on a dialysis schedule of Monday, Wednesday, and Friday.

Lab Values

• Glucose: 114 mg/dL

• Hematocrit: 40%

• Hemoglobin: 10.8 g/dL

• Potassium: 3.1 mmol/L

• Sodium: 135 mmol/L

Clinical Interpretation

Can intervention be initiated?

Take a moment to consider this before moving forward.

In reviewing Mr. Z’s labs, the potassium level stands out. At 3.1, it is at the lower end of the acceptable treatment range—but not yet critical. This is not unusual in patients receiving dialysis. Sodium is also on the low side, but still above the threshold of 130, so it’s not an immediate concern in terms of restricting activity.

Given these labs, yes, therapy can be initiated—but with precautions.

I would monitor his vital signs and physiologic response closely, especially because of the borderline low potassium. Hypokalemia can predispose patients to arrhythmias and other symptoms during exertion.

When to Stop Treatment

You must be prepared to terminate the session immediately if any of the following occur:

• Dizziness that does not resolve within 60 seconds of standing

• An increase in heart rate of 30 bpm or more above baseline, or signs of bradycardia or arrhythmia

• A rise in systolic blood pressure by more than 30 mmHg, or a diastolic increase greater than 10 mmHg, or signs of orthostatic hypotension

• Nausea or vomiting during activity

• New or worsening paresthesia (tingling or numbness)

• Onset of chest pain or anginal symptoms

In these cases, the session should be stopped immediately, vitals reassessed, and the medical team notified if symptoms persist.

Clinical Case #4

Mrs. R is an 80-year-old female admitted to the hospital with an exacerbation of congestive heart failure (CHF). Her past medical history includes diabetes mellitus (DM), hypertension (HTN), and a three-vessel coronary artery bypass graft (CABG) performed five years ago.

Her vital signs have remained stable, but due to her cardiac history, a set of three troponin levels, starting at 1400, was ordered yesterday.

Troponin Results

• 1400: <18

• 2000: 80

• 2400: 80

Current Vital Signs (taken at 0800)

• Blood pressure: 140/82

• Heart rate: 98 bpm

• Oxygen saturation: 94% on 2L O₂  via nasal cannula

Clinical Interpretation

Would you initiate treatment for Mrs. R?

Yes, I would initiate treatment. While her troponin levels rose from undetectable to 80 and remained stable at that level, they are still under the critical threshold of 100. This value is elevated above the normal cutoff of 18, but does not clearly indicate myocardial infarction. In this case, the troponins are considered indeterminate.

Given that her symptoms and vital signs are stable, and her history includes CHF, this level of troponin could reflect her chronic cardiac condition rather than an acute event. Therefore, I would proceed with therapy while continuing to monitor her physiologic response and remain in communication with the medical team in case her cardiac status changes.

Clinical Case #5

Mrs. T was admitted after experiencing a non-ST wave elevation myocardial infarction, commonly referred to as an NSTEMI. She has been hospitalized for two days, and therapy has been consulted to initiate cardiac rehabilitation.

Her troponin level peaked at 5,000 in the emergency department. Her most recent value is 2,000.

Current Vital Signs

• Blood pressure: 130/85

• Heart rate: 80 bpm

• Oxygen saturation: 95% on room air

Dr. N has indicated that Mrs. T is being considered for discharge today.

What confirms that Mrs. T had a heart attack?

The clearest indicator is her troponin level. A peak of 5,000 confirms myocardial damage consistent with a true infarction. While her levels have since decreased, they are still elevated at 2,000.

Why are her troponins still high after two days?

Troponins remain elevated in the bloodstream for up to a week following a cardiac event. These cardiac enzymes are released due to myocardial injury and gradually decline over time. Since it has not yet been a whole week since her MI, an elevated level of 2,000 is expected.

Is she appropriate for the initiation of cardiac rehab today?

Yes. It has been more than 24 hours since her troponin peak, and she is currently hemodynamically stable. Her blood pressure, heart rate, and oxygen saturation are within acceptable ranges for initiating low-level cardiac rehabilitation. Based on these findings and physician clearance, she can begin therapy safely.

Clinical Case #6

Mr. X was admitted to the hospital following a motor vehicle accident. He presents with a large, infected wound on his left leg, which is currently being treated with intravenous antibiotics. He also sustained a fracture to his left femur and has been in the intensive care unit for the past three days.

PT and OT services have been consulted to begin mobilizing him out of bed and initiating functional tasks such as gait training and activities of daily living (ADLs).

Lab Values

• Hemoglobin: 8.4 g/dL

• White blood cell (WBC) count: 12,000

• PTT: 30 seconds

• CPK: 340 U/L

• CPK-MB: less than 5% of total CPK

Clinical Interpretation

What issues might the therapist need to consider when treating Mr. X, given his hemoglobin level of 8.4?

According to clinical guidelines, a hemoglobin above 8 is generally safe for routine therapy. However, since this value is still on the lower end—and likely lower than the patient's baseline—you may observe:

• Increased fatigue

• Mental status changes

• Low exercise tolerance

• Tachycardia

• Dizziness

• Orthostatic hypotension

These symptoms are often related to reduced oxygen-carrying capacity in the blood, which can impact physical performance and safety during therapy.

Why might his white blood cell count be elevated?

A WBC count of 12,000 can indicate an active infection or inflammatory response. In this case, the elevation is likely due to the bacterial infection in his leg wound, which is already being treated with antibiotics. Many illnesses, especially infections, can cause a rise in white blood cell count.

What is the normal range for PTT in a patient not receiving anticoagulation?

For patients not on heparin, the normal range for PTT (partial thromboplastin time) is approximately 22 to 36 seconds. Mr. X’s PTT of 30 seconds falls within that normal range, indicating that his clotting ability is not currently impaired.

Why might his CPK be elevated?

CPK (creatine phosphokinase) levels increase in response to muscle injury. Mr. X’s elevated CPK of 340 likely reflects damage to skeletal muscle resulting from the trauma he sustained in the accident, particularly from the large wound and femur fracture. Since the CPK-MB fraction is less than 5% of the total, there is no indication of cardiac muscle injury.

Summary

In summary, lab values and vital signs are essential clinical tools that help guide decisions about whether a patient is appropriate for acute care rehabilitation. They provide a window into a patient's current physiologic status and help us assess whether it is safe to proceed with evaluation or intervention.

Equally important, however, is your observation of the patient’s real-time response during therapy. While lab values and vital signs offer valuable data points, they do not replace clinical judgment. Always monitor how the patient tolerates intervention, because safe and effective care depends on both objective data and skilled observation.

Throughout this course, we’ve reviewed key strategies for chart review, emphasized the role of lab values and vitals in decision-making, and explored when and why to hold or modify treatment sessions. These are foundational skills for delivering high-quality, patient-centered care in the acute care setting.

Questions and Answers

What are the common daily reasons therapy might be held?

Some of the most typical reasons therapy may be postponed or held include:

• Hemoglobin levels dropping below 7 g/dL

• A patient undergoing evaluation for a possible DVT

• Elevated or peaking troponin levels

These three situations—low hemoglobin, suspected DVT, and acute cardiac markers—are among the most frequent flags that delay or prevent intervention on any given day.

A personal example: recognizing change in a familiar patient

I recently went through this with my mother, who is 80 and has a history of low hemoglobin. I could often tell just by looking at her when her levels had dropped. Her fatigue would increase dramatically, and her ability to complete daily tasks would noticeably decline. I'd sometimes encourage her to get her blood tested simply based on those observations.

Do you see that kind of immediate change in the hospital setting?

Yes, but it varies. You may not have access to daily labs in home care, so you rely more heavily on patient observation and behavior. In the hospital, we usually have the advantage of updated lab results every 24 hours, often available first thing in the morning, alongside continuous vital signs. This helps us compare trends over time and make more informed decisions.

In acute care, sudden drops can occur more quickly, perhaps due to bleeding, infection, or worsening of the primary diagnosis. Therapists are often among the first clinicians to identify subtle or acute changes, like new weakness, changes in mentation, or coordination deficits, especially when baseline knowledge of the patient is taken into account.

How should documentation reflect therapy being held?

It’s always best to document as specifically as possible. For example:
"OT deferred treatment today due to hemoglobin of 6.7. Will readdress when appropriate."
That level of clarity is helpful for both communication and compliance. Facilities may vary in preferred phrasing, but noting the lab value and rationale directly helps reduce ambiguity and supports continuity of care.

Do you have tips for referencing lab thresholds?

A: Having quick reference guidelines on hand is essential. We relied more on memory in the past, but now therapists can use smartphones or printed tools to keep track of red flag thresholds. That's why we’ve worked to simplify our protocol into a set of “top three labs to check” and clearly marked caution zones, so it’s easier for staff to recall what matters most.

Have therapy holds changed over time?

Yes. Over the years, we’ve shifted from rigid lab cut-offs to a more nuanced, patient-centered approach. Now, we do more risk-benefit analysis based on the whole clinical picture. For example, even if a hemoglobin level is slightly below a traditional threshold, I may still proceed with therapy if:

• The physician explicitly requests intervention

• I’m able to monitor the patient’s vital signs

• I feel confident I can detect early signs of clinical deterioration

In such cases, I document carefully that treatment was initiated per the physician's request and outline the precautions taken.

Have you experienced pressure from administration to treat despite concerns?

Our institution is fortunate to have a culture that encourages professional judgment and conversation. While there is an emphasis on documentation and throughput—such as ensuring timely evaluations for rehab disposition—we're rarely pressured to meet time-based metrics.

If a patient is medically unstable or at risk of harm, I advocate firmly for their safety. On the other hand, if therapy can be safely modified to reduce exertion—like simulating ADLs at the bedside rather than a full mobility session—I may proceed to ensure functional assessment without overtaxing the patient. The context always matters.

References

Please refer to the reference handout