American Board of Internal Medicine (ABIM) Certification Practice Exam

Gitelman syndrome is associated with the clinical mimicry of what type of diuretic?

1. Thiazide diuretics

2. Loop diuretics

3. Potassium-sparing diuretics

4. Osmotic diuretics

The correct answer is: Thiazide diuretics

Gitelman syndrome is a genetic disorder characterized by a set of clinical features that resemble those caused by the use of thiazide diuretics. This condition results from a deficiency in the Sodium-Chloride Cotransporter (NCC) in the distal convoluted tubule, leading to a series of electrolyte imbalances, including hypokalemic metabolic alkalosis, hypomagnesemia, and hypocalciuria. The clinical presentation of Gitelman syndrome mimics that of thiazide diuretic use because thiazides inhibit the reabsorption of sodium and chloride in the same area of the nephron where the mutation occurs. Patients with Gitelman syndrome often exhibit similar symptoms to those who experience the side effects of thiazide therapy, such as muscle cramps, weakness, and fatigue due to increased urinary loss of electrolytes. In contrast, loop diuretics primarily act on the loop of Henle and lead to different patterns of electrolyte depletion, while potassium-sparing diuretics typically maintain potassium levels or even lead to hyperkalemia. Osmotic diuretics cause different physiological changes by increasing osmolality in the tubular fluid, affecting water reabsorption rather than directly altering sodium or chloride transport. Therefore,