AEMCA Practice Exam

What is a common osmotic diuretic?

1. Bendroflumethiazide

2. Hydrochlorothiazide

3. Mannitol

4. Furosemide

The correct answer is: Mannitol

Mannitol is a widely recognized osmotic diuretic that functions primarily by increasing the osmolarity of the blood and renal tubular fluid. This increase in osmolarity results in the retention of water in the kidneys, which leads to increased urine output. Mannitol is often utilized in clinical settings for conditions that require rapid diuresis, such as preventing renal failure or reducing intracranial pressure. In contrast, the other choices listed are different types of diuretics, which do not primarily operate through the osmotic mechanism. Bendroflumethiazide and hydrochlorothiazide are thiazide diuretics that act on the distal convoluted tubule to inhibit sodium reabsorption, while furosemide is a loop diuretic that works on the loop of Henle to block sodium and chloride reabsorption. These classes of diuretics primarily affect electrolyte and fluid balance through different physiological pathways, rather than through the osmotic effect that characterizes mannitol.