These are the lab ranges most nursing programs and the NCLEX expect you to know. Exact ranges vary a little between labs, so always use your facility's values on the job.
Electrolytes
| Lab | Normal range | Watch for |
|---|---|---|
| Sodium | 135 to 145 mEq/L | Confusion and seizures when too low or too high |
| Potassium | 3.5 to 5.0 mEq/L | Dangerous heart rhythms when too low or too high |
| Chloride | 98 to 106 mEq/L | Often moves with sodium |
| Calcium | 9.0 to 10.5 mg/dL | Low: muscle twitching, tingling. High: weakness, kidney stones |
| Magnesium | 1.5 to 2.5 mg/dL | Low: tremors, irregular rhythms |
| Phosphorus | 3.0 to 4.5 mg/dL | Often opposite to calcium |
Glucose and kidney labs
| Lab | Normal range |
|---|---|
| Fasting glucose | 70 to 100 mg/dL |
| Hemoglobin A1C | Below 5.7% |
| BUN | 10 to 20 mg/dL |
| Creatinine | 0.6 to 1.2 mg/dL |
Complete blood count
| Lab | Normal range |
|---|---|
| Hemoglobin | Men 14 to 18 g/dL, women 12 to 16 g/dL |
| Hematocrit | Men 42% to 52%, women 37% to 47% |
| White blood cells | 5,000 to 10,000 per mm³ |
| Platelets | 150,000 to 400,000 per mm³ |
Clotting labs
| Lab | Normal | On treatment |
|---|---|---|
| INR | 0.8 to 1.1 | Usually 2 to 3 on warfarin |
| aPTT | 30 to 40 seconds | About 1.5 to 2.5 times normal on a heparin drip |
Arterial blood gases
| Value | Normal range |
|---|---|
| pH | 7.35 to 7.45 |
| PaCO2 | 35 to 45 mm Hg |
| HCO3 | 22 to 26 mEq/L |
| PaO2 | 80 to 100 mm Hg |
Need help reading a blood gas? See ABG interpretation with ROME.
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Quick answers
What is a normal potassium level?
3.5 to 5.0 mEq/L. Levels outside this range can cause dangerous heart rhythms.
What is a normal INR?
About 0.8 to 1.1. For most patients taking warfarin, the goal is usually 2 to 3.
Evidence & Clinical Sources
- MedlinePlus lab tests
- Hinkle & Cheever, Brunner & Suddarth's Textbook of Medical-Surgical Nursing, Wolters Kluwer
Reviewed against current guidelines and drug labels. Always follow your program, a current drug reference, and facility policy. Our sources policy
For learning only. Lab ranges and policies vary. Always follow your nursing program, a current drug reference, and your facility's policies.