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.
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.
Ready to practice for real?
Work through the full NCLEX-RN question bank with detailed rationales for every answer.
Open the Question BankRelated reading
How to Study for the NCLEX in 30 Days: A Day-by-Day Plan
A realistic 30-day NCLEX study plan broken into weekly focus areas, daily question targets, and review strategy.
Best NCLEX Question Banks in 2026: Free vs Paid Compared
A comparison of free and paid NCLEX question banks in 2026, covering question volume, rationale quality, and NGN case study support.
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.