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These are the reference ranges NCLEX questions are written around — commonly used adult values from standard nursing review sources. For each one, learn the normal range, the panic direction (which way harms the client), and the nursing action tied to it. This page is print-styled — print it.
Electrolytes
| Value | Normal | Remember |
|---|---|---|
| Sodium (Na⁺) | 135–145 mEq/L | Neuro changes both directions — seizures at extremes |
| Potassium (K⁺) | 3.5–5.0 mEq/L | The cardiac one. High or low → dysrhythmias; check EKG |
| Calcium (Ca²⁺) | 9.0–10.5 mg/dL | Low → Chvostek/Trousseau, tetany; high → stones, groans |
| Magnesium (Mg²⁺) | 1.3–2.1 mEq/L | Low Mg often travels with low K⁺ and low Ca²⁺ |
Renal & glucose
| Value | Normal | Remember |
|---|---|---|
| BUN | 10–20 mg/dL | Rises with dehydration, not just kidney injury |
| Creatinine | 0.6–1.3 mg/dL | The kidney number. Trending up = renal impairment |
| Glucose (fasting) | 70–110 mg/dL | <70 = treat the hypoglycemia first |
| HbA1c (diabetic goal) | <7% | 3-month average control |
CBC
| Value | Normal | Remember |
|---|---|---|
| Hemoglobin | M 14–18 · F 12–16 g/dL | Oxygen carrier — fatigue, pallor when low |
| Hematocrit | M 42–52% · F 37–47% | ≈ 3 × Hgb |
| WBC | 5,000–10,000 /mm³ | <5,000 → neutropenic precautions territory |
| Platelets | 150,000–400,000 /mm³ | <50,000 bleeding risk — soft toothbrush, no razors, fall precautions |
Coagulation
| Value | Normal | Remember |
|---|---|---|
| INR | 0.8–1.1 (warfarin: 2–3) | High INR → hold warfarin; vitamin K is the antidote |
| aPTT | 30–40 sec (heparin: 1.5–2×) | Heparin follows aPTT; protamine sulfate is the antidote |
ABGs
| Value | Normal | Remember |
|---|---|---|
| pH | 7.35–7.45 | <7.35 acidosis · >7.45 alkalosis |
| PaCO₂ | 35–45 mmHg | Respiratory driver — opposite to pH = respiratory cause |
| HCO₃⁻ | 22–26 mEq/L | Metabolic driver — same direction as pH = metabolic cause |
| PaO₂ | 80–100 mmHg | <80 = hypoxemia |
ROME: Respiratory Opposite, Metabolic Equal — the fastest way to classify an ABG on exam day.
Therapeutic drug levels
| Drug | Therapeutic | Remember |
|---|---|---|
| Digoxin | 0.5–2.0 ng/mL | Toxicity: nausea, vision changes, bradycardia — check apical pulse & K⁺ |
| Lithium | 0.6–1.2 mEq/L | >1.5 toxic — tremor, GI upset; keep sodium and fluids steady |
| Phenytoin | 10–20 mcg/mL | Toxicity: ataxia, nystagmus, gingival hyperplasia |
How to actually memorize these
Don't drill numbers in a vacuum — attach each to the action it triggers (low K⁺ → hold digoxin, check EKG). CinnaRN turns every value into a swipeable card with its nursing action and shows it inside real questions, so the number sticks because you used it. Browse the free cheat-sheet library or practice in the app.