BMP Components
Sodium (Na): 135-145 mEq/L. Potassium (K): 3.5-5.0 mEq/L. Chloride (Cl): 98-107 mEq/L. CO2 (bicarbonate): 22-29 mEq/L. BUN: 7-20 mg/dL. Creatinine: 0.6-1.3 mg/dL (men), 0.5-1.1 (women). Glucose: 70-100 mg/dL (fasting). Anion gap: 8-12 mEq/L. BUN:Cr ratio: 10:1-20:1. Calculate: eGFR for renal function. Critical: Na <120 or >160, K <2.5 or >6.5, glucose <40 or >500, CO2 <10.
CMP Additional
Total protein: 6.0-8.3 g/dL. Albumin: 3.5-5.0 g/dL. Total bilirubin: 0.3-1.2 mg/dL. Direct bilirubin: 0.0-0.3. Alkaline phosphatase (ALP): 44-147 IU/L. AST: 10-40 IU/L. ALT: 7-56 IU/L. Calcium: 8.5-10.5 mg/dL (corrected for albumin). Phosphorus: 2.5-4.5 mg/dL. Magnesium: 1.7-2.2 mg/dL (often separate). CMP: liver function, calcium, protein in addition to BMP.
Abnormal Patterns
Na: hyponatremia (seizures if <120), hypernatremia (seizures if >160). K: hypokalemia (arrhythmias, U waves), hyperkalemia (peaked T waves, arrhythmias). Ca: hypocalcemia (tetany, Chvostek/Trousseau), hypercalcemia (stones, bones, groans). BUN:Cr ratio >20:1 suggests prerenal AKI. AST/ALT elevated: liver injury. Bilirubin elevated: jaundice. Glucose: diabetes management. Corrected calcium = measured Ca + 0.8 x (4.0 - albumin).
Important Notes
- Correct sodium replacement slowly (<8-10 mEq/L in 24h) to prevent osmotic demyelination syndrome.
- Peaked T waves on ECG are an early sign of hyperkalemia — check K+ and treat immediately if >6.5.
Clinical Tips
- Corrected calcium = measured Ca + 0.8 x (4.0 - albumin) — low albumin lowers total calcium, but ionized calcium may be normal.
- BUN:Cr ratio >20:1 suggests prerenal AKI (dehydration, bleeding, decreased perfusion).
Summary
CMP/BMP interpretation requires knowing normal ranges, recognizing abnormal patterns (electrolytes, renal, liver, glucose), and implementing appropriate interventions.
