NCLEX Lab Values Cheat Sheet + Practice Questions
A quick-reference NCLEX lab values cheat sheet plus practice questions on abnormal labs and the correct nursing action for each.
Published by Nurse Moose · Practice Questions
You don't need to memorize every lab value in the body — you need to instantly recognize which values are dangerously abnormal and what to do about them. Here's a quick-reference table followed by practice questions.
Quick-reference table
| Lab | Normal range | Critical note |
|---|---|---|
| Potassium (K+) | 3.5–5.0 mEq/L | Cardiac risk above 6.0 or below 2.5 |
| Sodium (Na+) | 135–145 mEq/L | Neuro symptoms below 120 or above 160 |
| Calcium (Ca2+) | 9.0–10.5 mg/dL | Tetany/seizure risk if very low |
| Glucose (fasting) | 70–100 mg/dL | Below 70 = hypoglycemia action needed |
| Platelets | 150,000–400,000/mm³ | Bleeding risk below 50,000 |
| INR (on warfarin) | 2.0–3.0 (therapeutic) | Above 4–5 = bleeding risk |
| Hemoglobin | 12–17 g/dL (varies by sex) | Below 7–8 often triggers transfusion |
| Creatinine | 0.6–1.2 mg/dL | Rising trend = worsening kidney function |
Practice questions
1. A client's INR is 6.5. Which action does the nurse anticipate?
- A. Increase the warfarin dose
- B. Hold warfarin and prepare to administer vitamin K
- C. Administer protamine sulfate
- D. No action needed, this is therapeutic
Show answer & rationale
Correct answer: B
An INR of 6.5 is well above the therapeutic range (2–3) and indicates serious bleeding risk; warfarin should be held and vitamin K given per provider order. Protamine reverses heparin, not warfarin.
2. Which client's platelet count requires the nurse to implement bleeding precautions?
- A. 250,000/mm³
- B. 180,000/mm³
- C. 45,000/mm³
- D. 300,000/mm³
Show answer & rationale
Correct answer: C
A platelet count below 50,000/mm³ significantly increases bleeding risk and requires precautions such as a soft toothbrush, electric razor, and avoiding IM injections.
3. A client's fasting blood glucose is 58 mg/dL and they are alert. What should the nurse do first?
- A. Give 15–20 g of fast-acting carbohydrate
- B. Administer insulin
- C. Recheck in 4 hours
- D. Notify the provider before treating
Show answer & rationale
Correct answer: A
For a conscious, symptomatic hypoglycemic client, the nurse should immediately give 15–20 g of fast-acting carbohydrate per the 'Rule of 15,' then recheck glucose in 15 minutes.
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Frequently asked questions
Which lab values are highest-yield for the NCLEX?
Potassium, sodium, glucose, INR/PTT, and platelets are tested most frequently because they drive immediate nursing actions.
Do I need to memorize exact normal ranges?
You need close approximations and, more importantly, you need to recognize when a value is dangerous enough to require action — that clinical judgment is what NCLEX actually tests.
Official exam information
For current exam requirements and scoring, consult the official NCLEX test plans and candidate resources. This article is study guidance, not official exam content, medical advice or a guarantee of passing.