Loop diuretics can cause which electrolyte abnormality?

Loop diuretics can cause which electrolyte abnormality?

• A. Hyperkalemia
• B. Hyponatremia
• C. Hypokalemia
• D. Hypercalcemia

Answer: (C)

Loop diuretics block the Na-K-2Cl cotransporter in the thick ascending limb, so more sodium, chloride, and water are excreted. The increased sodium delivery to the distal tubule drives more potassium (and hydrogen) secretion there, especially with aldosterone, leading to potassium loss in the urine. This is why hypokalemia is the classic electrolyte abnormality associated with loop diuretics. They also increase calcium excretion, which can lower serum calcium, so hypercalcemia isn’t expected. Hyperkalemia would point to other drug effects, not loop diuretics.

Loop diuretics block the Na-K-2Cl cotransporter in the thick ascending limb, so more sodium, chloride, and water are excreted. The increased sodium delivery to the distal tubule drives more potassium (and hydrogen) secretion there, especially with aldosterone, leading to potassium loss in the urine. This is why hypokalemia is the classic electrolyte abnormality associated with loop diuretics. They also increase calcium excretion, which can lower serum calcium, so hypercalcemia isn’t expected. Hyperkalemia would point to other drug effects, not loop diuretics.