Lab Values for Nurses

Normal ranges, critical values, causes, and when to call — every lab a nurse checks on shift.

White Blood Cells4,500–11,000 /mm³ HemoglobinM 14–18 g/dL · F 12–16 g/dL HematocritM 42–52% · F 37–47%Platelets150,000–400,000 /mm³ Mean Corpuscular Volume80–100 fL Sodium136–145 mEq/L Potassium3.5–5.0 mEq/L Chloride98–106 mEq/L CO₂23–30 mEq/L Blood Urea Nitrogen10–20 mg/dL CreatinineM 0.6–1.2 mg/dL · F 0.5–1.1 mg/dL Glucose70–99 mg/dL (fasting)Calcium9.0–10.5 mg/dL Magnesium1.3–2.1 mEq/L Phosphorus3.0–4.5 mg/dL Prothrombin Time11–12.5 seconds INR0.8–1.1 (no anticoagulant) · therapeutic on warfarin: usually 2.0–3.0 (2.5–3.5 mechanical valve)aPTT30–40 s · therapeutic on heparin: typically 1.5–2.5× control (per protocol)D-dimer< 0.4 µg/mL FEU (lab-specific)Fibrinogen200–400 mg/dL Troponin< 0.04 ng/mL (conventional; hs assays lab-specific)BNP / NT-proBNPBNP < 100 pg/mL · NT-proBNP < 300 pg/mL (age-adjusted)pH7.35–7.45 PaCO₂35–45 mmHg PaO₂80–100 mmHg HCO₃⁻22–26 mEq/L Lactate0.5–2.2 mEq/L AST10–40 U/L (values vary by lab)ALT7–56 U/L (values vary by lab)Alkaline Phosphatase44–147 U/L Bilirubin0.3–1.0 mg/dL Albumin3.5–5.0 g/dL Ammonia10–80 µg/dL (lab-specific)TSH0.4–4.0 mIU/L (lab-specific)Hemoglobin A1c< 5.7% normal · 5.7–6.4% prediabetes · ≥ 6.5% diabetes · goal on treatment usually < 7%Digoxin level0.5–2.0 ng/mL (HF goal often 0.5–0.9)Lithium level0.6–1.2 mEq/L (maintenance)Vancomycin trough10–20 µg/mL (target depends on indication; AUC dosing where used)Phenytoin level10–20 µg/mL (total; correct for low albumin)C-Reactive Protein< 1.0 mg/dL (< 10 mg/L)Urine Specific Gravity1.005–1.030

Educational reference for nurses and nursing students — not medical advice, diagnosis, or treatment. Always verify against your facility's current policies, the prescriber, and pharmacy.

Lab Values for Nurses

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