In patients with CrCl < 30 mL/min, which diuretic should be avoided due to hyperkalemia risk?

• A. Spironolactone
• B. Furosemide
• C. Hydrochlorothiazide
• D. Amiloride

Answer: (A)

Potassium-sparing diuretics carry a high risk of hyperkalemia when kidney function is reduced. Spironolactone blocks aldosterone receptors in the distal nephron, which decreases potassium excretion. In someone with CrCl <30 mL/min, the kidneys are already poor at excreting potassium, so adding spironolactone markedly increases the risk of dangerous hyperkalemia. That’s why it’s avoided in this setting according to Beers Criteria.

The other diuretics listed are not typically associated with hyperkalemia in this context: loop diuretics like furosemide increase potassium loss (potassium-depleting), and thiazides like hydrochlorothiazide also promote potassium loss. Amiloride is potassium-sparing as well, but spironolactone is the classic agent flagged for this risk in advanced CKD.