Which of the following conditions can contribute to hypokalemia?

• A. Metabolic acidosis
• B. Diuretic therapy
• C. Hyperkalemia
• D. Renal failure

Answer: (B)

Hypokalemia happens when potassium loss in the body is greater than intake or when potassium shifts into cells. Diuretic therapy is a classic cause because loop and thiazide diuretics increase sodium delivery to the distal nephron. That boost in sodium reabsorption via ENaC in the collecting ducts drives more potassium to be secreted into the urine, and the accompanying volume depletion from diuretics activates the renin-angiotensin-aldosterone system, which further promotes potassium loss. The result is a lower serum potassium level.

Metabolic acidosis tends to raise potassium levels because excess hydrogen ions enter cells in exchange for potassium leaving cells, so it commonly causes hyperkalemia rather than hypokalemia. Renal failure impairs potassium excretion, also favoring hyperkalemia. Hyperkalemia itself is high potassium, not low, so it wouldn’t contribute to hypokalemia. Therefore, diuretic therapy best explains the development of hypokalemia among the options.