Lab Value Interpretation

Original Editor - Ayelawa Samuel Top Contributors - Ayelawa Samuel, Kim Jackson, Lucinda hampton and Rachael Lowe


Lab values.jpg
Physical therapists should not rely exclusively on a single laboratory finding; they should also consider a variety or other clinical factors. Likewise, it is important to understand the significance of trends in the values over time[1]. Laboratory value tests are one factor in determining the overall health of our patients. For many tests, the normal ranges will vary depending on age, gender, race, or other factors[2].

Risk and benefit considerations to therapeutic intervention

The fundamental consideration when reviewing patient laboratory findings is toward determining an appropriate plan of care and weighing the anticipated benefit of a therapy intervention against the potential of the patient. Physical therapists should carefully anticipate the physiological changes that might have occurred whenever a laboratory value is out of range. They should also be aware of the heightened risk level if a value should fall into the critical range. It is critical to understand pertinent lab values and the subsequent potential of adverse events when practicing in this kind of practice setting. To begin or continue interventions on patients that we’re seeing in the acute care setting, we always need to use clinical decision making[1].  The Lab values alone may or may not determine whether you’re going to intervene with a patient, or whether you’re going to hold[2].

Things to consider when looking at the patient’s condition

  • Potential drug interactions
  • Significant trends in the values over time
  • Electrolyte panels might change with intravenous infusions, medications, and diet
  • Chronic medical conditions (such as anemia) might be asymptomatic during exercise, while a patient with precipitous drop in hemoglobin and hematocrit might require urgent medical attention.


Lab values Normal range Rehabilitation consideration
Hematocrit(%RBC) 43-49%(male)    


No exercise (<25%)

light exercise (25-30%)

Resistive exercise (>30%)

Platelets 150,000-350,000/µL No exercise (<20,000µL)

Light exercise (20,000-50,000µL)

Resistive exercise (>50,000µL)

Hemoglobin 14.4-16.6gm/dL (male)

12.2-14.7gm/dl (female)

No exercise (<8gm/dl)

light exercise (8-10gm/dl)

Resistive exercise (>10gm/dl)

White blood cell(WBC)    4,500-11,000 mm3 No exercise (<5,000 mm3 )

Light exercise (>5,000 mm3)

Resistive exercise (>5,000 mm3 as tolerated)


Lab values Normal range Rehabilitation consideration
Sodium  135-145mEq/L Reduction: Cramps, weakness, confusion

Elevation: Fluid retention, Swelling, Hypertension

Potassium  3.5-5.0mEq/L Reductions: Flattened T waves, arrthymias

Elevations: Peaked T waves, shortened QT interval

Calcium  8.5-10.5mg/dl     Reductions (Moderate to severe): parathesias, muscle spasms and seizure and

QT interval prolongation.

Elevations (severe only): Bradycardia, AV block, and short QT interval, coma

Magnesium         1.7 to 2.2mg/dl  Reductions: prolonged PR or QT intervals, T-Waves flattening or inversion, SVT.

Elevation: weakness, respiratory failure, coma, paralysis.

Chloride  95-105mEq/L       Reduction: often occur during metabolic alkalosis

Elevations: Metabolic acidosis


Lab values Normal range Rehabilitation consideration
Prothrombin time(PTT) 11-12.5sec Assesses extrinsic pathway (fast system)

Therapeutic range: 1-2 times normal

Risk of bleeding: >2-3 times normal

International normalized

Ratio (INR)

0.9-1.1   normalized ratio PT, used to assess effect of warfarin

therapeutic range: Afib/DVT/PE (2-3)

Valve replacement (2.5-3.5)

Risk of bleeding: >4.0 light exercise only

>5.0 hold exercise, PT eval only

>6.0 PT contraindication

The outline was created to assist the clinician with lab value considerations for the general population. The clinician should be aware that “norm” are created for the healthy adult, and each patient’s lab value should be interpreted within the context of the patient’s current medical status[1]. Pediatrics population lab values range is not included above.

The video below gives a good introduction to lab values and normal ranges



  1. 1.0 1.1 1.2 1.   James T., Traci N., Kim L. Academy of Acute Care Physical Therapy-APTA Task Force on Lab Values. Laboratory values interpretation Resource. 2017
  2. 2.0 2.1 Available from:
  3. Flashcard Machine: available from:
  4. 4.0 4.1 1.      Physical Therapy Reviewer. Available from:  
  5. Khanacacemymedicine. Introduction to lab values and normal ranges | Health & Medicine | Khan Academy. Available from: (last accessed 26.4.2019)