Normal lab values cheat sheet for nursing students

Lab values test judgment, not memorization: know the range, then know what an abnormal value means for your patient.

Reference ranges vary slightly between labs and textbooks, and NCSBN does not publish an official list. These are commonly taught ranges; always use your facility's ranges in practice.

Built from NurseLingo's RN-written study decks· Updated Oct 2026· Sources

Lab	Normal range	Why it matters
Sodium (Na+)	135-145 mEq/L	Fluid balance & nerve conduction Correct slowly - protects brain
Potassium (K+)	3.5-5.0 mEq/L	Critical for cardiac rhythm High or low = arrhythmias
Calcium (Ca++)	8.6-10.2 mg/dL	Bone, clotting, muscle contraction Low: Chvostek, Trousseau signs
Magnesium (Mg++)	1.3-2.1 mEq/L	Neuromuscular & cardiac function Low: tremors, high: lost reflexes
Fasting Glucose	70-99 mg/dL	Under 70 = hypoglycemia Treat with 15g carbs
BUN	7-20 mg/dL	Rises with dehydration Renal impairment marker
Creatinine	0.6-1.2 mg/dL	Key kidney function marker
Hemoglobin (Hgb)	M 14-17.4, W 12-16 g/dL	Low = anemia Watch fatigue, pallor
Platelets	150,000-400,000/uL	Under 50k = bleeding precautions
WBC	5,000-10,000/uL	High = infection Low = immunosuppression risk
INR	Goal 2.0-3.0 on warfarin	2.5-3.5 for some mechanical valves
ABG - pH	7.35-7.45	Under 7.35 = acidosis Over 7.45 = alkalosis

RN pearl: Know the number, then ask why - labs test judgment, not memorization. Put it on your lock screen - it studies you back.

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▶ Lab Values Made Easy for Nursing Students · 13:02 · free on the Nurse Lingo YouTube channel

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Frequently asked questions

What is the normal potassium level?

3.5 to 5.0 mEq/L. Both high and low potassium can cause dangerous heart rhythms.

What is the normal sodium level?

135 to 145 mEq/L. Abnormal sodium is corrected slowly to protect the brain.

What is a therapeutic INR on warfarin?

2.0 to 3.0 for most clients, and 2.5 to 3.5 for some clients with mechanical heart valves.

At what platelet count are bleeding precautions needed?

Under 50,000 per microliter.

Keep studying

⚡ Speed MatchSort drugs, lab values and electrolyte signs NCLEX lab values flashcardsStudy online free Electrolyte imbalances cheat sheetFluids & electrolytes Therapeutic drug levels cheat sheetPharmacology ABG interpretation cheat sheetAcid-base

Sources

Fundamentals of Nursing, Appendix A: Adult Lab Values, OpenStax
Clinical Nursing Skills, Appendix A: Adult Lab Values, OpenStax
Pharmacology for Nurses, 20.2 Anticoagulants, OpenStax
Comprehensive metabolic panel, MedlinePlus, U.S. National Library of Medicine

For study only, not medical advice. Ranges and protocols vary by facility; follow your program and facility policies.