Which electrolyte abnormality is most likely with loop diuretic use?

Which electrolyte abnormality is most likely with loop diuretic use?

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

Answer: (B)

Loop diuretics block the Na-K-2Cl cotransporter in the thick ascending limb, so more Na, Cl, and water are excreted and less is reabsorbed. The increased sodium delivery to the distal nephron drives more potassium secretion into the urine, and volume loss activates systems that further promote potassium loss. The net result is low potassium in the blood, i.e., hypokalemia. They can also cause magnesium wasting and increased calcium excretion, but the most likely and clinically important electrolyte change is hypokalemia.