Prescribing Safety Assessment (PSA) Practice Exam

Which diuretics are primarily responsible for causing hypokalemia?

1. Thiazides

2. Loop Diuretics

3. Potassium-sparing Diuretics

4. Both Loop Diuretics and Thiazides

The correct answer is: Both Loop Diuretics and Thiazides

Thiazide diuretics and loop diuretics are both known for their ability to induce hypokalemia, which is a lower than normal level of potassium in the blood. Thiazide diuretics, such as hydrochlorothiazide, work on the distal convoluted tubule of the nephron by inhibiting sodium reabsorption. This impairment in sodium reabsorption leads to increased sodium delivery to the distal nephron, which then causes increased potassium secretion and excretion, often resulting in hypokalemia. Loop diuretics, including furosemide, act on the ascending limb of the loop of Henle and have a similar effect. They inhibit sodium reabsorption, resulting in significant diuresis and increased potassium secretion through the distal nephron, which also contributes to hypokalemia. Potassium-sparing diuretics, on the other hand, function by either antagonizing the action of aldosterone or directly blocking sodium channels, which helps to retain potassium rather than causing its loss. This is why potassium-sparing diuretics are not associated with hypokalemia. Given that both thiazide and loop diuretics are known to cause hypokalemia as a common side effect, the option indicating that