Which electrolyte disturbance is most characteristic of vomiting?

• A. Hyperkalemic Metabolic Acidosis
• B. Hypokalemic Hypochloremic Metabolic Alkalosis
• C. Hyperkalemic Metabolic Alkalosis
• D. Hypophosphatemia Metabolic Acidosis

Answer: (B)

Vomiting causes loss of gastric acid (hydrogen and chloride) and fluid, so the body develops a metabolic alkalosis with low chloride—hypochloremic metabolic alkalosis. The accompanying volume depletion activates aldosterone, which drives renal potassium and hydrogen ion loss, leading to hypokalemia. This combination—low chloride, low potassium, and metabolic alkalosis—is the classic picture associated with vomiting. Other patterns, like hyperkalemic metabolic acidosis or metabolic acidosis with hypophosphatemia, don’t fit the typical response to vomiting.