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MBBS QUESTION #10377
Question 1
A patient with prolonged vomiting develops hypochloremic, hypokalemic metabolic alkalosis. The biochemical basis for the accompanying hypokalemia in this setting includes:
  • Renal potassium wasting, driven partly by aldosterone-mediated compensation for volume depletion, which promotes exchange of potassium (and hydrogen ions) for sodium reabsorption in the distal nephron✔️
  • Direct loss of potassium in vomited gastric contents as the sole significant mechanism
  • Increased dietary potassium intake during illness
  • Decreased renal excretion of potassium in this setting
Correct Answer Explanation
Vomiting causes loss of gastric acid (H+ and Cl-) directly, but the resulting volume depletion activates the renin-angiotensin-aldosterone system; aldosterone-driven sodium reabsorption in the distal nephron is coupled to potassium and hydrogen ion secretion, compounding both the hypokalemia and the metabolic alkalosis in a self-perpetuating cycle ('paradoxical aciduria').