Hydrochlorothiazide can decrease potassium. True or False?

Hydrochlorothiazide can decrease potassium. True or False?

• A. Decreases potassium
• B. Increases potassium
• C. No effect on potassium
• D. Increases calcium

Answer: (A)

Thiazide diuretics block the NaCl cotransporter in the distal convoluted tubule, so less NaCl is reabsorbed there. More sodium reaches the collecting duct, and its reabsorption drives potassium secretion into the urine via lumen-negative forces. That increases potassium loss and lowers serum potassium, so hydrochlorothiazide can decrease potassium. A separate effect of thiazides is increased calcium reabsorption in the distal tubule, which reduces calcium excretion, but that doesn’t change the potassium outcome.

Thiazide diuretics block the NaCl cotransporter in the distal convoluted tubule, so less NaCl is reabsorbed there. More sodium reaches the collecting duct, and its reabsorption drives potassium secretion into the urine via lumen-negative forces. That increases potassium loss and lowers serum potassium, so hydrochlorothiazide can decrease potassium. A separate effect of thiazides is increased calcium reabsorption in the distal tubule, which reduces calcium excretion, but that doesn’t change the potassium outcome.