A plain-language reference for clinicians: what common blood tests measure, typical adult ranges, what to watch for during therapy and when to call the physician.
Reviewed by Dr. Richard Holsman, PT, DPT, NCS · Last reviewed November 13, 2026 · How we review
For detailed lab-by-lab guidance written for physical therapists, including how values relate to activity decisions in acute care, use the Laboratory Values Interpretation Resource from the APTA Academy of Acute Care Physical Therapy and the APTA Academy of Pediatric Physical Therapy (updated December 2023). It is free for physical therapists, physical therapist assistants and students who register with the Academy. This page is our own shorter, plain-language overview and is not a copy or summary of that resource.
Full citation: Joint Task Force of the APTA Academy of Acute Care Physical Therapy and the APTA Academy of Pediatric Physical Therapy. Laboratory Values Interpretation Resource. Updated December 2023. PDF · Academy product page.
Jump to: Quick table · Complete blood count (CBC) · Electrolytes · Blood sugar · Kidney function · Blood clotting · Heart markers · Other useful labs · When to call · Sources
Adult ranges as published by the sources in brackets. Your lab’s own range takes priority. Tap a test name for details.
| Test | Typical adult range | Watch for in therapy | Source |
|---|---|---|---|
| Hemoglobin | M 13.8–17.2 g/dL; F 12.1–15.1 g/dL | Fatigue, lightheaded on standing, short of breath | [1] |
| Hematocrit | M 37%–48%; F 34%–43% | Read with hemoglobin | [2] |
| Platelets | 150,000–400,000/µL | Bruising, bleeding; fall injury | [3] |
| WBC | 4,500–11,000/µL | Infection or inflammation | [6] |
| ANC | Neutropenia below 1,500/µL; severe below 500 | Infection risk, fever | [4] |
| Potassium | 3.7–5.2 mEq/L | Palpitations, irregular pulse, weakness | [8] |
| Sodium | 135–145 mEq/L | Confusion, cramps, unsteadiness | [11] |
| Calcium | 8.8–10.3 mg/dL | Weakness, confusion, bone pain | [13] |
| Magnesium | 1.7–2.2 mg/dL | Cramps, weakness, numbness | [15] |
| Glucose (fasting) | 70–99 mg/dL; low below 70 | Shaky, sweaty, confused | [17, 18] |
| A1C | Normal below 5.7% | Long-term diabetes control | [20] |
| BUN | 6–20 mg/dL | Dehydration, dizziness | [21] |
| Creatinine | M 0.7–1.3; F 0.5–0.95 mg/dL | Rise from baseline | [22] |
| eGFR | 90–120 mL/min/1.73 m²; CKD below 60 for 3+ months | Fluid and electrolyte shifts | [23] |
| PT / INR | PT 11–13.5 s; INR 0.8–1.1 (warfarin target often 2.0–3.0) | Bleeding, falls, head strike | [24] |
| PTT | 25–35 s | Bleeding on heparin | [25] |
| Troponin | Lab-specific cut-off | Chest pain, new rise | [26] |
| BNP | Below 100 pg/mL makes heart failure unlikely | Swelling, weight gain, breathlessness | [28] |
| Albumin | 3.4–5.4 g/dL | Nutrition | [29] |
| Lactate | 0.5–2.2 mmol/L | Low oxygen to tissues, sepsis | [30] |
M = men, F = women. mEq/L = milliequivalents per liter. µL = microliter.
What it measures. The oxygen-carrying protein in red blood cells.
Typical adult range. Men 13.8–17.2 g/dL; women 12.1–15.1 g/dL.[1]
Why it matters in therapy. A low value (anemia) can come from bleeding, chronic illness, kidney disease, poor nutrition or bone-marrow problems.[1] Mild anemia may cause no symptoms. As it worsens, people tire faster with exercise, feel lightheaded when they stand up, get short of breath with light activity or even at rest, and look pale.[5] In therapy, that means watching for dizziness on sit-to-stand and transfers, taking vital signs before and during activity, and using rest breaks and fall precautions.
When to contact the physician. New or worsening symptoms (shortness of breath at rest, dizziness or near-fainting, chest discomfort), any sign of new bleeding, or a clear drop from the patient’s previous result.
What it measures. The share of blood volume made up of red blood cells. It is part of every CBC and tracks closely with hemoglobin.
Typical adult range. Men 37%–48%; women 34%–43%.[2]
Why it matters in therapy. Read it together with hemoglobin. A low hematocrit raises the same concerns as anemia: reduced exercise tolerance and dizziness with position changes. Dehydration can push red-cell values up, so a dry patient may look less anemic than they are.[1]
When to contact the physician. Same as hemoglobin: new symptoms, signs of bleeding or a falling trend.
What it measures. Cell fragments that start blood clotting.
Typical adult range. 150,000–400,000 per microliter (150–400 × 109/L). Below 150,000 is low (thrombocytopenia). Below 50,000, bleeding risk is higher and even everyday activities can cause bleeding.[3]
Why it matters in therapy. A low count raises the stakes of a fall or any bump. Look for easy bruising or bleeding, guard closely during gait and balance work, and be cautious with any technique that applies firm pressure. Cancer treatment, some medicines and autoimmune disorders are common causes.[3]
When to contact the physician. Any new bleeding, a fall with head strike, a sudden severe headache, or a count that is falling. Check facility policy for activity limits at low counts.
What it measures. The total number of infection-fighting white cells. The ANC counts neutrophils, the white cells that fight bacterial and fungal infection; it is the WBC multiplied by the percentage of neutrophils and bands.[4]
Typical adult range. WBC 4,500–11,000 per microliter (4.5–11.0 × 109/L).[6] Neutrophils usually make up 40%–60% of white cells.[7] Neutropenia is graded by ANC: mild 1,000–1,500, moderate 500–1,000, severe below 500 per microliter. The usual lower limit is about 1,500 and is somewhat lower in Black patients (about 1,200).[4]
Why it matters in therapy. A high WBC can point to infection or inflammation. A low ANC means the patient fights infection poorly: below 500, even the body’s own mouth and gut bacteria can cause infection.[4] Use strict hand hygiene, clean shared equipment, consider scheduling the patient away from anyone who is sick, and follow any neutropenic precautions ordered.
When to contact the physician. Fever, chills or any new sign of infection in a patient with a low ANC is urgent. Also report an unexpectedly high or rising WBC with new symptoms.
What it measures. The main electrolyte inside cells; it is essential for normal nerve, muscle and heart-rhythm function.
Typical adult range. 3.7–5.2 mEq/L (mmol/L).[8]
Why it matters in therapy. Low potassium often comes from diuretics, vomiting or diarrhea. It can cause weakness, cramps and palpitations, and a large drop can trigger abnormal heart rhythms, lightheadedness or fainting, especially in people with heart disease.[9] High potassium is linked to kidney disease and to some medicines (ACE inhibitors, ARBs, potassium-sparing diuretics). It often causes no symptoms, but it can cause palpitations, a slow, weak or irregular pulse, and sudden collapse.[8][10] Check the pulse for regularity, ask about palpitations, and watch the heart-rate response to activity.
When to contact the physician. Any abnormal value with palpitations, an irregular or unusually slow pulse, chest pain, new weakness, shortness of breath or lightheadedness. Treat collapse as an emergency.
What it measures. The main electrolyte outside cells; it reflects the balance of salt and water in the body.
Typical adult range. 135–145 mEq/L.[11]
Why it matters in therapy. Low sodium can cause confusion, irritability, headache, fatigue, muscle weakness or cramps, nausea and, when severe, seizures.[12] New confusion or unsteadiness raises fall risk. High sodium is often a sign of fluid loss or of not drinking enough, which is more likely in people who cannot sense thirst or reach fluids because of cognitive impairment.[11]
When to contact the physician. New or worsening confusion, headache with nausea, or seizure. A large drop in sodium can be a life-threatening emergency.[12]
What it measures. Total blood calcium, needed for bone, muscle contraction, nerve signaling and heart rhythm.
Typical adult range. 8.8–10.3 mg/dL (2.20–2.58 mmol/L).[13]
Why it matters in therapy. Prolonged bed rest is one of the listed causes of high calcium, along with hyperparathyroidism and cancers that affect bone.[13] High calcium can cause muscle weakness, fatigue, confusion, increased thirst and urination, nausea or constipation, and bone pain with fragile bones.[14] That makes early mobilization relevant, and it is a reason to take new bone pain seriously.
When to contact the physician. Abnormal calcium with confusion, new weakness, bone pain or palpitations.
What it measures. A mineral that supports muscle, nerve and heart-rhythm function.
Typical adult range. 1.7–2.2 mg/dL (0.70–0.91 mmol/L).[15]
Why it matters in therapy. Low magnesium is linked to alcohol use disorder, uncontrolled diabetes, chronic diarrhea, kidney disease and medicines such as diuretics and proton pump inhibitors.[15] It can cause muscle cramps or spasms, weakness, fatigue, numbness and, when severe, convulsions.[16] Low magnesium often travels with low potassium, so look at both.
When to contact the physician. Symptoms of low magnesium. A large drop can be a life-threatening emergency.[16]
What it measures. The amount of sugar in the blood at the time of the test.
Typical adult range. Fasting 70–99 mg/dL (3.9–5.5 mmol/L). A random (non-fasting) value is usually 125 mg/dL or lower.[17] Blood sugar below 70 mg/dL is low (hypoglycemia).[18]
Why it matters in therapy. Exercise lowers blood sugar, so low readings matter most in patients who take insulin or other glucose-lowering medicines. Signs of low blood sugar include shaking, sweating, hunger, a fast or pounding heartbeat, headache, blurred vision, unclear thinking and, when much lower (below 54 mg/dL), seizures.[18] For people with type 1 diabetes, the American Diabetes Association’s 2016 position statement suggests a pre-exercise blood glucose of 90–250 mg/dL. Below 90 mg/dL it suggests 15–30 g of fast-acting carbohydrate before starting. From 250 mg/dL up, it advises testing for ketones, no exercise if moderate-to-large ketones are present, and only mild-to-moderate exercise until glucose comes down.[19] Ask diabetic patients to bring their meter and a fast-acting carbohydrate to sessions.
When to contact the physician. Low blood sugar that does not improve after a sugary snack, a patient who becomes less alert or cannot be woken (call 911), or high glucose with ketones present.[18][19]
What it measures. The average blood sugar over the previous 3 months.[20]
Typical adult range. Below 5.7% is normal; 5.7%–6.4% is prediabetes; 6.5% or higher is in the diabetes range (diagnosis needs two abnormal results). For many people with diabetes, the goal is below 7%. Anemia, kidney or liver disease, some blood disorders and recent transfusion can make A1C inaccurate.[20]
Why it matters in therapy. A1C does not tell you whether it is safe to exercise today; a current glucose reading does. It does show how well diabetes has been controlled over recent months, which is useful background when you plan exercise and check glucose around sessions.
When to contact the physician. A1C is not usually a reason for same-day contact. Share a markedly high result with the physician if it does not appear to have been addressed.
What it measures. A waste product of protein breakdown, cleared by the kidneys.
Typical adult range. 6–20 mg/dL.[21]
Why it matters in therapy. A high BUN can come from dehydration, heart failure, kidney disease or bleeding in the gut.[21] Dehydration adds to orthostatic dizziness, so read BUN together with creatinine, blood pressure and symptoms.
When to contact the physician. A rising BUN with dizziness, low blood pressure, black or bloody stools, or new swelling and shortness of breath.
What it measures. A waste product of normal muscle metabolism, cleared almost entirely by the kidneys.
Typical adult range. Men 0.7–1.3 mg/dL (62–115 µmol/L); women 0.5–0.95 mg/dL (44–84 µmol/L). Levels depend on body size and muscle mass.[22]
Why it matters in therapy. A rise means the kidneys are clearing less. Because the value depends on muscle mass, a frail older adult can have a “normal” creatinine with reduced kidney function. Reduced kidney function affects fluid balance, electrolytes (especially potassium) and how long some medicines last.
When to contact the physician. A sudden rise from the patient’s baseline, or reduced urine output with swelling or shortness of breath.
What it measures. An estimate of how much blood the kidneys filter each minute, calculated from creatinine and other factors.
Typical adult range. Normal is about 90–120 mL/min/1.73 m². It falls with age. Below 60 for 3 months or more is a sign of chronic kidney disease; below 15 is a sign of kidney failure that needs immediate medical attention.[23]
Why it matters in therapy. Patients with chronic kidney disease often have anemia, fatigue, fluid shifts and electrolyte problems. For patients on dialysis, plan sessions around treatment times and follow the dialysis team’s instructions about the access arm.
When to contact the physician. An eGFR below 15 that is new or not being managed, or a sudden drop from baseline.[23]
What it measures. How long blood takes to clot through one pathway. The INR standardizes the PT so results can be compared across labs; it is used to monitor warfarin.
Typical adult range. Without blood thinners: PT 11–13.5 seconds, INR 0.8–1.1. On warfarin, the target INR is most often 2.0–3.0. Above 3.0 raises bleeding risk further; below 2.0 can leave a patient at risk for a clot.[24]
Why it matters in therapy. A patient on an anticoagulant bleeds more easily, and a fall can mean an internal or head bleed. Reinforce fall prevention, guard closely, watch for bruising, blood in the urine or stool, and report any fall with a head strike. A low INR in a patient being treated for a clot is also worth noticing.
When to contact the physician. Any fall or head strike in an anticoagulated patient, new bleeding, a severe headache, or an INR well outside the patient’s target range.
What it measures. How long blood takes to clot through another pathway; it is used to monitor heparin.[25]
Typical adult range. Generally 25–35 seconds. It is longer in people taking blood thinners.[25]
Why it matters in therapy. Same bleeding and fall considerations as a high INR. A patient on a heparin drip has frequent PTT checks; follow the facility’s activity plan for that patient.
When to contact the physician. New bleeding, a fall, or a value flagged as outside the target range for the patient’s heparin protocol.
What it measures. A protein released when heart muscle is injured. It is the main blood test for a heart attack and is usually repeated over 6 to 24 hours.[26]
Typical adult range. There is no single number to memorize. Each lab sets its own cut-off for its assay (many now use high-sensitivity tests). Even a small rise often means some heart damage. Most people having a heart attack have a raised level within 6 hours, and it can stay high for 1 to 2 weeks.[26]
Why it matters in therapy. Troponin can also rise with a very fast heart rate, pulmonary embolism, heart failure, myocarditis, pulmonary hypertension and prolonged endurance exercise.[26] A new or rising troponin means the medical team is still working out whether the heart is being injured, so check with them before exercise.
When to contact the physician. A new or rising troponin, or any chest pain, pressure or shortness of breath during therapy. Stop activity and follow your facility’s emergency procedure.
What it measures. Hormones the heart releases when it is working harder to pump. They are used to help confirm or rule out heart failure.[27]
Typical adult range. BNP below 100 pg/mL suggests heart failure is unlikely; above 100 is abnormal, and higher values make heart failure more likely and more severe.[28] Normal NT-proBNP depends on age and sex, so read it against the lab’s own range.[27] Obesity can make levels read low, and kidney failure, pulmonary embolism and pulmonary hypertension can raise them.[27]
Why it matters in therapy. In a patient with known heart failure, a rising BNP or NT-proBNP fits with worsening fluid overload. Watch for weight gain, new swelling, shortness of breath lying flat, and reduced exercise tolerance, and monitor vital signs and perceived exertion during sessions.
When to contact the physician. A marked rise from baseline, or new signs of fluid overload (swelling, rapid weight gain, shortness of breath at rest or lying flat).
What it measures. The main protein in blood plasma, made by the liver.
Typical adult range. 3.4–5.4 g/dL (34–54 g/L).[29]
Why it matters in therapy. A low albumin can point to liver disease, kidney disease or poor intake or absorption of nutrients.[29] In therapy it is a flag to ask about nutrition and to involve the dietitian or physician, especially in a patient who is losing weight or strength.
When to contact the physician. A low albumin that has not been addressed in a patient with weight loss, poor intake or new swelling.
What it measures. A product of metabolism that builds up when tissues are not getting enough oxygen.
Typical adult range. 0.5–2.2 mmol/L (4.5–19.8 mg/dL).[30]
Why it matters in therapy. A raised lactate means tissues are short of oxygen. Causes include sepsis, heart failure, lung disease, liver disease, low blood oxygen and some medicines, such as metformin.[30] Treat a high value as a reason to check with the medical team before activity.
When to contact the physician. A raised lactate before therapy, or signs of sepsis or low oxygen during a session (fever, fast breathing, confusion, low blood pressure).
This is clinician education, not medical advice. It does not replace the lab’s reference ranges, your facility’s policies, physician orders or your own clinical judgment. Patients with questions about their results should talk with the doctor who ordered the test.
Related clinician tools: Wells Criteria for DVT · Revised Geneva & Constans Scores · 6-Minute Walk Test · All clinician tools
Every number on this page was checked against the source listed for it on November 13, 2026. Grade key: A = clinical guideline or professional-society position statement; B = professional clinical reference written for clinicians; C = U.S. government health reference (National Library of Medicine).
Recommended reference (not used as a source for this page). Joint Task Force of the APTA Academy of Acute Care Physical Therapy and the APTA Academy of Pediatric Physical Therapy. Laboratory Values Interpretation Resource. Updated December 2023. academy.aptaacutecare.org.
Clinical review. Reviewed by Dr. Richard Holsman, PT, DPT, NCS, Board-Certified Clinical Specialist in Neurologic Physical Therapy and founder of Holsman Physical Therapy. Last reviewed: November 13, 2026.
Review policy. We review this page at least once a year, and sooner when a cited source changes its ranges or guidance. Ranges come only from sources we have opened and checked; anything we could not verify is left out. Report an error to richard@holsmanhealthcare.com.
Change log. November 13, 2026: first version published.
Licensing. Text and table layout © 2026 Holsman Physical Therapy and Wellness, P.C., written in our own words. Reference ranges are factual values credited to the sources above. Nothing on this page is reproduced from the APTA Academy resource.
Disclosure. Holsman Physical Therapy owns this website and provides physical therapy services. This page carries no advertising and no sponsorship, and we receive nothing for any link on it. We are not affiliated with the American Physical Therapy Association, its academies, the National Library of Medicine, Merck & Co. or the American Diabetes Association, and they do not endorse this website.
Blood test results help a therapist decide whether today is a safe day to exercise a patient, how closely to monitor vital signs and symptoms, and when something should go back to the physician before therapy continues. Low hemoglobin, an abnormal potassium, a low platelet count or a high INR can each change how a session is run.
No. Reference ranges differ from lab to lab and by method, and some tests, such as troponin, have cut-offs that each lab sets for its own assay. Always read a result against the range printed on that lab’s report and follow your facility’s policy.
No. This page explains what each test means and what to watch for. Decisions to hold, change or continue therapy belong to the treating clinician working with the physician, under facility policy and physician orders. For acute care, the APTA Academy of Acute Care Physical Therapy and Academy of Pediatric Physical Therapy publish the Laboratory Values Interpretation Resource, the standard reference for physical therapists.
MedlinePlus defines low blood sugar as below 70 mg/dL. The American Diabetes Association’s 2016 position statement, written for people with type 1 diabetes, suggests a pre-exercise target of 90 to 250 mg/dL and 15 to 30 g of fast-acting carbohydrate before exercise when glucose is below 90 mg/dL. Follow the patient’s diabetes plan and your facility’s protocol.
No. This is education for licensed clinicians and students. Patients with questions about their own results should ask the doctor who ordered the test.
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