Reference
Laboratory values and the action each one demands.
NCLEX rarely asks you only to recognise an abnormal value — it asks what the nurse does next. Read every row as value plus action.
Electrolytes
- Sodium135–145 mEq/Lcritical <120 or >160 mEq/L
Assess neuro status and seizure risk; correct slowly to avoid cerebral shifts.
- Potassium3.5–5.0 mEq/Lcritical <2.5 or >6.5 mEq/L
Place on cardiac monitor; never IV push potassium; hold digoxin if low.
- Calcium (total)9.0–10.5 mg/dLcritical <7 or >13 mg/dL
Check Trousseau/Chvostek if low; seizure and fall precautions.
- Magnesium1.3–2.1 mEq/Lcritical <1.0 or >4.0 mEq/L
Assess deep tendon reflexes and respirations; calcium gluconate is the antidote.
Renal and metabolic
- BUN10–20 mg/dLcritical >100 mg/dL
Evaluate hydration and renal perfusion; review nephrotoxic medications.
- Creatinine0.6–1.2 mg/dLcritical >4 mg/dL
Recalculate renal-dosed drugs; monitor intake, output and daily weight.
- Glucose (fasting)70–110 mg/dLcritical <50 or >400 mg/dL
Treat hypoglycemia with 15 g fast carbohydrate; recheck in 15 minutes.
- Hemoglobin A1C<5.7% (target <7% in diabetes)critical >10%
Reinforce self-monitoring, diet and medication adherence teaching.
Hematology and coagulation
- Hemoglobin12–16 g/dL female · 14–18 g/dL malecritical <7 g/dL
Assess for fatigue, dyspnea and tachycardia; institute fall precautions.
- Platelets150,000–400,000/mm³critical <50,000/mm³
Bleeding precautions: soft toothbrush, no IM injections, no rectal temps.
- INR0.8–1.1 (2–3 on warfarin)critical >5
Hold warfarin and notify provider; vitamin K is the antidote.
- aPTT30–40 sec (1.5–2.5× on heparin)critical >100 sec
Stop heparin infusion; protamine sulfate is the antidote.
Arterial blood gases
- pH7.35–7.45critical <7.20 or >7.60
Identify respiratory vs metabolic cause; assess airway and level of consciousness.
- PaCO₂35–45 mm Hgcritical >60 mm Hg
Support ventilation; rising CO₂ with drowsiness signals impending failure.
- HCO₃⁻22–26 mEq/Lcritical <10 mEq/L
Look for DKA, sepsis or renal loss; monitor for Kussmaul respirations.
- PaO₂80–100 mm Hgcritical <60 mm Hg
Apply oxygen, raise the head of the bed, and reassess after intervention.
Draft demonstration item — requires clinical review.