Acute vomiting can lead to which acid-base disturbance?

• A. Metabolic Acidosis: due to loss of bicarbonate in diarrhea
• B. Respiratory alkalosis
• C. Metabolic alkalosis: due to loss of hydrogen/chloride ions
• D. Metabolic acidosis due to renal failure

Answer: (C)

Vomiting removes gastric acid, specifically hydrogen ions and chloride, from the body. Losing these acidic components shifts the balance toward a higher bicarbonate level in the blood, producing a metabolic alkalosis. The volume loss from vomiting can further promote bicarbonate retention by the kidneys, worsening the alkalosis, while the body attempts to compensate with a slower, more shallow breathing pattern to retain carbon dioxide—though this respiratory compensation is limited in the acute setting. This scenario is distinct from other disturbances: diarrhea typically causes metabolic acidosis from bicarbonate loss, and hyperventilation causes respiratory alkalosis. So acute vomiting most commonly leads to metabolic alkalosis due to loss of hydrogen and chloride ions.