Vomiting leads to which acid-base disturbance?

• A. Metabolic acidosis with hyperkalemia
• B. Respiratory alkalosis
• C. Metabolic acidosis with hypochloremia
• D. Hypochloremic metabolic alkalosis with hypokalemia

Answer: (D)

Vomiting results in loss of gastric acid (hydrogen ions) and chloride. Losing H+ raises the body’s bicarbonate relative to hydrogen, producing a metabolic alkalosis. The concurrent loss of chloride causes hypochloremia, and the volume depletion that accompanies vomiting activates aldosterone-driven renal losses of hydrogen and potassium, leading to hypokalemia and further sustaining the alkalosis. This pattern—hypochloremic metabolic alkalosis with hypokalemia—fits vomiting best, whereas other disturbances would require different primary imbalances (for example, metabolic acidosis or a primary respiratory change).