NCLEX Lab Values Every Nursing Student Must Know 2026

Lab values are one of the most tested topics on NCLEX, ATI, and HESI exams. Here are ALL the critical lab values you must memorize for 2026. ## Complete NCLEX Lab Values Reference 2026 ### Electrolytes | Lab | Normal Range | Critical Values | |-----|-------------|-----------------| | Sodium (Na) | 135-145 mEq/L | <120 or >160 | | Potassium (K) | 3.5-5.0 mEq/L | <2.5 or >6.5 | | Calcium (Ca) | 8.5-10.5 mg/dL | <7 or >12 | | Magnesium (Mg) | 1.6-2.6 mEq/L | <1 or >3 | | Phosphorus | 2.5-4.5 mg/dL | — | | Chloride | 97-107 mEq/L | — | ### Complete Blood Count (CBC) | Lab | Normal Range | |-----|-------------| | WBC | 5,000-10,000/mm3 | | RBC Male | 4.5-6.0 million/mm3 | | RBC Female | 4.0-5.5 million/mm3 | | Hemoglobin Male | 14-18 g/dL | | Hemoglobin Female | 12-16 g/dL | | Hematocrit Male | 42-52% | | Hematocrit Female | 37-47% | | Platelets | 150,000-400,000/mm3 | ### Coagulation Studies | Lab | Normal Range | |-----|-------------| | PT | 11-12.5 seconds | | INR | 0.8-1.1 (therapeutic 2-3) | | aPTT | 30-40 seconds (therapeutic 60-80) | | Bleeding time | 1-9 minutes | ### Metabolic Panel | Lab | Normal Range | |-----|-------------| | Glucose | 70-110 mg/dL | | BUN | 10-20 mg/dL | | Creatinine | 0.6-1.2 mg/dL | | Total Protein | 6.4-8.3 g/dL | | Albumin | 3.5-5.0 g/dL | | Total Bilirubin | 0.3-1.0 mg/dL | ### Cardiac Markers | Lab | Normal Range | |-----|-------------| | Troponin I | <0.04 ng/mL | | CK-MB | 0-3% | | BNP | <100 pg/mL | | Myoglobin | 0-85 ng/mL | ### Thyroid Function | Lab | Normal Range | |-----|-------------| | TSH | 0.4-4.0 mIU/L | | T3 | 80-200 ng/dL | | T4 | 5-12 mcg/dL | ### Arterial Blood Gas (ABG) | Lab | Normal Range | |-----|-------------| | pH | 7.35-7.45 | | PaCO2 | 35-45 mmHg | | PaO2 | 80-100 mmHg | | HCO3 | 22-26 mEq/L | | SaO2 | 95-100% | ## ABG Interpretation — ROME Method - **Respiratory Opposite**: pH up = CO2 down (alkalosis); pH down = CO2 up (acidosis) - **Metabolic Equal**: pH up = HCO3 up (alkalosis); pH down = HCO3 down (acidosis) ## Critical Values — Call the Doctor IMMEDIATELY - K+ <2.5 or >6.5 — cardiac arrhythmias - Na+ <120 or >160 — neurological changes - Glucose <50 or >500 — altered consciousness - Platelet <50,000 — bleeding risk - INR >3 — bleeding risk on warfarin Download complete lab value study guides on Studyrift — verified for NCLEX 2026! 🩺