Case: The patient underwent serum chemistry and arterial blood gas. Patient was found to have Na of 139 meq/l, K 3 meq/l, CL 93 meq/L and HCO₃ of 35. Patient pH was 7.49 and pCO₂ was 41. What is the underlying acid base disturbance.

A) Mixed Respiratory and Metabolic Alkalosis
B) Respiratory Alkalosis
C) Hyperchloremic non-anion gap metabolic acidosis  
D) Metabolic Alkalosis




Answer: D. Metabolic alkalosis

Rationale: Patient has pH of 7.49 suggestive of alkalosis. pCO₂ is within normal range excluding respiratory alkalosis. The pH is high and chloride is 93 meq/L showing no indication of hyperchoremic metabolic acidosis. HCO₃ is high and expected pCO₂is within normal range (Expected CO₂=0.9 x HCO₃+9; .9X35+9=40.5) suggestive of simple compensated metabolic alkalosis as seen with diuretic therapy.