Laxative overuse can cause which metabolic disturbance?

Laxative overuse can cause which metabolic disturbance?

• A. Hyperkalemia, metabolic acidosis
• B. Hypokalemia, metabolic alkalosis
• C. Hyperkalemia, metabolic alkalosis
• D. Hypokalemia, metabolic acidosis

Answer: (B)

Laxative overuse often leads to chronic diarrhea and volume depletion. When the body detects low blood volume, the renin–angiotensin–aldosterone system is activated. Aldosterone increases Na+ reabsorption in the distal nephron in exchange for K+ and H+ secretion. This drives potassium loss (hypokalemia) and hydrogen ion loss, producing a metabolic alkalosis. Loss of chloride with stool can further favor alkalosis by reducing the kidney’s ability to excrete bicarbonate. So the combination of low potassium and a raised bicarbonate (metabolic alkalosis) fits best with laxative overuse.

Laxative overuse often leads to chronic diarrhea and volume depletion. When the body detects low blood volume, the renin–angiotensin–aldosterone system is activated. Aldosterone increases Na+ reabsorption in the distal nephron in exchange for K+ and H+ secretion. This drives potassium loss (hypokalemia) and hydrogen ion loss, producing a metabolic alkalosis. Loss of chloride with stool can further favor alkalosis by reducing the kidney’s ability to excrete bicarbonate. So the combination of low potassium and a raised bicarbonate (metabolic alkalosis) fits best with laxative overuse.