📌 How to use these rangesNormal lab values and therapeutic ranges may vary slightly by lab, facility, textbook, or school. For exams, follow the reference range provided in the question. In clinical practice, always follow your facility policy, provider orders, and the lab's stated reference range.
1. Complete Blood Count (CBC)
| Test | Normal Range |
|---|
| WBC | 4,500–11,000 cells/µL |
| RBC (male) | 4.6–6.2 million cells/µL |
| RBC (female) | 4.2–5.4 million cells/µL |
| Hemoglobin (male) | 13–18 g/dL |
| Hemoglobin (female) | 12–16 g/dL |
| Hematocrit (male) | 40–55% |
| Hematocrit (female) | 36–48% |
| Platelets | 150,000–400,000/µL |
2. Electrolytes & Basic Metabolic Panel
| Test | Normal Range |
|---|
| Sodium (Na⁺) | 135–145 mEq/L |
| Potassium (K⁺) | 3.5–5.0 mEq/L |
| Chloride (Cl⁻) | 95–105 mEq/L |
| BUN | 7–20 mg/dL |
| Creatinine | 0.6–1.2 mg/dL |
| Fasting glucose | 70–100 mg/dL |
| Calcium (total) | 9.0–11.0 mg/dL (varies by lab) |
| Magnesium | 1.7–2.2 mg/dL |
| Phosphorus | 2.5–4.5 mg/dL |
| Urine specific gravity | 1.005–1.030 |
🧪 Calcium range varies by labPassclex uses 9.0–11.0 mg/dL for total calcium. Reference ranges vary by lab — use the range provided in the question or your facility policy.
⚠️ Magnesium unitsUse 1.7–2.2 mg/dL. Some nursing references teach 1.5–2.5 mEq/L — that is a different unit, so never write 1.5–2.5 mg/dL. Low magnesium causes neuromuscular irritability and dysrhythmias; high magnesium causes decreased reflexes, respiratory depression, and cardiac depression.
3. Arterial Blood Gases (ABG)
| Test | Normal Range |
|---|
| pH | 7.35–7.45 |
| PaCO₂ | 35–45 mmHg |
| HCO₃⁻ | 22–26 mEq/L |
| PaO₂ | 80–100 mmHg |
| SaO₂ / SpO₂ | 95–100% |
| COPD oxygen target | often 88–92% when ordered |
4. Coagulation
| Test | Normal / Target |
|---|
| PT | 11–13.5 seconds |
| INR (not on warfarin) | 0.8–1.1 |
| INR (typical warfarin goal) | 2.0–3.0 |
| INR (mechanical heart valve) | 2.5–3.5 |
| PTT / aPTT | 25–35 seconds |
| Therapeutic heparin aPTT | 1.5–2.5× control (≈46–70 sec) |
🎯 PT is in seconds — INR is a ratioPT is measured in seconds. INR is a ratio, never seconds. PTT/aPTT monitors heparin; PT/INR monitors warfarin.
5. Therapeutic Drug Levels
| Drug | Therapeutic Range |
|---|
| Digoxin | 0.5–2.0 ng/mL |
| Lithium (maintenance) | 0.6–1.2 mEq/L |
| Lithium (acute mania) | up to 1.5 mEq/L |
| Lithium toxicity | >1.5 mEq/L (severe often >2.0–2.5) |
| Phenytoin | 10–20 mcg/mL |
| Valproic acid | 50–100 mcg/mL |
| Carbamazepine | 4–12 mcg/mL |
| Theophylline | 10–20 mcg/mL |
| Vancomycin (trough) | 10–20 mcg/mL |
| Gentamicin / tobramycin (trough) | <2 mcg/mL |
💡 DigoxinNarrow therapeutic index (0.5–2.0 ng/mL). Hold if the adult apical pulse is below 60 bpm, and monitor potassium — hypokalemia increases digoxin toxicity risk.
6. Diabetes / Glucose
| Test | Value |
|---|
| Fasting blood glucose | 70–100 mg/dL |
| HbA1c — normal | <5.7% |
| HbA1c — prediabetes | 5.7–6.4% |
| HbA1c — diabetes | ≥6.5% |
| DKA glucose | usually >250 mg/dL |
| HHS / HHNS glucose | often >600 mg/dL |
7. Vital Signs & Common Values
| Item | Normal Range |
|---|
| Adult heart rate | 60–100 bpm |
| Adult respiratory rate | 12–20/min |
| Adult temperature | ~97.8–99°F (36.5–37.2°C) |
| Adult SpO₂ | 95–100% |
| Adult urine output | at least 30 mL/hr |
| Fetal heart rate (baseline) | 110–160 bpm |