4.5 Lab Values PTAs Must Recognize
Key Takeaways
- Hemoglobin (Hgb) below 7-8 g/dL typically holds aerobic exercise; 8-10 g/dL supports light activity only; above 10 g/dL allows standard progression per Plan of Care (POC).
- Platelets below 20,000 cells per microliter generally hold all physical therapy; 20,000-50,000 supports light Activities of Daily Living (ADLs) and active range of motion only; above 50,000 allows resistive exercise per POC.
- International Normalized Ratio (INR) above 4-5 puts the patient at high bleeding and falls risk; PTAs implement fall precautions and verify with nursing or the supervising Physical Therapist (PT).
- Blood glucose under 100 mg/dL usually warrants a snack before exercise; values at or above 250-300 mg/dL with ketones, or at or above 300 mg/dL, generally hold exercise.
- Exact hold-thresholds vary by facility, diagnosis, and POC; the PTA always checks the chart and confirms with the supervising PT, nursing, or medicine.
Why This Section Is on Almost Every NPTE-PTA Form
Lab values are the cleanest test items the NPTE-PTA can write: one number, one decision. Goodman and Snyder's Differential Diagnosis for Physical Therapists and Pierson and Fairchild's Principles and Techniques of Patient Care both publish hold/light/progress charts that the exam mirrors closely.
The table below uses common textbook ranges. Facilities may set tighter limits in their plans of care, so always check the chart and confirm with the supervising PT, nursing, or medicine before treating.
Hold-Exercise Thresholds (Adult, General)
| Lab | Normal Adult Range | Light Activity Only | Hold / Notify |
|---|---|---|---|
| Hemoglobin (Hgb) | 12-17 g/dL | 8-10 g/dL | less than 7-8 g/dL |
| Hematocrit (Hct) | 36-52% | 25-30% | less than 25% |
| White Blood Cells (WBC) | 4,500-11,000 per microliter | less than 5,000 with neutropenic precautions | less than 1,000 absolute neutrophils, or fever |
| Platelets | 150,000-400,000 per microliter | 20,000-50,000 (no resistive, no high-fall-risk) | less than 20,000 |
| International Normalized Ratio (INR) | 0.9-1.1 (no anticoagulation); 2.0-3.0 therapeutic | 3.0-4.0 with fall precautions | greater than 4-5 |
| Blood Glucose (random) | 70-140 mg/dL | less than 100 (snack first); 250-300 (monitor for ketones) | less than 70 with symptoms; 300+ with ketones or symptoms |
| Oxygen Saturation (SpO2) | 95% or higher | 90-94% on supplemental O2 | less than 88-90% per POC |
Hemoglobin and Hematocrit (Oxygen Carrying)
Low Hgb means the blood carries less oxygen, so submaximal effort feels much harder. Symptoms include tachycardia at rest, pallor, dyspnea on exertion, and chest pain. Coordinate with nursing - patients with active gastrointestinal (GI) bleeding or recent transfusion need re-checked labs before progressing.
Platelets and Bleeding Risk
Low platelets raise the risk of bleeding from minor trauma. The textbook rule of thumb:
- Above 50,000: resistive exercise is generally safe with normal precautions.
- 20,000-50,000: light ADLs, ambulation, AROM only. Avoid resistance, end-range stretch, and high-fall-risk activities.
- Below 20,000: hold therapy. Even a minor bump can produce a large bruise or joint bleed.
International Normalized Ratio (INR)
INR measures anticoagulation. Therapeutic targets are usually 2.0-3.0 (atrial fibrillation) or up to 2.5-3.5 (mechanical heart valves). Above 4-5, fall and bleeding risk rises sharply: use a gait belt, slow transfers, use environmental supports, and avoid any percussion or aggressive manual technique. Hold and notify the supervising PT and nurse when the chart shows new or rising INR plus any sign of bleeding (gums, nosebleed, blood in urine, large new bruise).
Blood Glucose
- Hypoglycemia (less than 70 mg/dL) is a medical emergency. Symptoms: shakiness, sweating, confusion, blurred vision. Per facility policy, follow the 15-15 rule (15 g of fast carbohydrate, recheck in 15 minutes).
- Pre-exercise less than 100 mg/dL: have the patient eat a small carbohydrate snack before activity to avoid an exercise-induced drop.
- At or above 250-300 mg/dL with ketones present or at or above 300 mg/dL generally holds exercise; exertion can worsen hyperglycemia and dehydration.
Workflow When a Lab Is Out of Range
- Verify the value is current (today's lab, not yesterday's).
- Re-check vital signs and screen for active symptoms.
- Cross-check the Plan of Care for any explicit exercise restrictions.
- Notify the supervising PT and nursing; document the value, your decision, the time, and the patient response.
- Choose the most conservative option that still allows safe care - sometimes that is bed-level AROM, sometimes it is hold and reassess later.
An oncology patient's morning labs show platelets of 18,000 per microliter and Hgb of 9.2 g/dL. The PTA was planning a resistance and gait training session. The most appropriate action is:
A patient with type 2 diabetes mellitus is about to start outpatient gait training. A fingerstick glucose just before therapy reads 86 mg/dL. The patient ate breakfast 2 hours ago. The PTA should:
A PTA notes a hospitalized patient on warfarin has a new INR of 5.6 and a new large bruise on the forearm. The PT had ordered standing balance and resisted hip exercise. The PTA should: