AEMCA Practice Exam

What is the mechanism of action of thiazide diuretics?

1. Inhibits aldosterone action

2. Inhibits reabsorption of sodium chloride at the distal convoluted tubule

3. Inhibits potassium absorption

4. Enhances calcium reabsorption

The correct answer is: Inhibits reabsorption of sodium chloride at the distal convoluted tubule

Thiazide diuretics primarily function by inhibiting the reabsorption of sodium chloride in the distal convoluted tubule of the nephron in the kidneys. This mechanism leads to an increase in the excretion of sodium and water, which results in a decrease in blood volume and consequently lowers blood pressure. By blocking the sodium-chloride transporter in this specific part of the nephron, thiazide diuretics effectively prevent sodium from being reabsorbed back into the bloodstream, causing the body to lose excess fluid and sodium through urine. The focus on the distal convoluted tubule is significant because it highlights where thiazide diuretics exert their primary effect, distinguishing them from other types of diuretics that target different areas of the nephron. The mechanism also allows for a secondary effect of enhancing calcium reabsorption, which can be beneficial in patients who may be at risk for osteoporosis.