AAMC FL Practice Exam

What is the primary role of aldosterone in the body?

1. Promotes potassium retention in the kidneys

2. Increases water retention through sodium retention

3. Decreases blood volume through urine production

4. Stimulates production of glucose in the liver

The correct answer is: Increases water retention through sodium retention

The primary role of aldosterone in the body is to increase water retention through sodium retention. Aldosterone is a steroid hormone produced by the adrenal glands, and it specifically acts on the kidneys to promote the reabsorption of sodium from the urine back into the bloodstream. This process is crucial because when sodium is reabsorbed, water follows osmotically. Consequently, this retention of sodium and the associated water leads to an increase in blood volume and blood pressure. While promoting potassium retention is also a function of aldosterone, its predominant mechanism involves the sodium-water balance. By regulating sodium levels in the body, aldosterone plays a fundamental role in maintaining fluid balance, electrolyte levels, and overall blood pressure within the circulatory system. The option that involves urine production as a means of decreasing blood volume does not capture the essence of aldosterone's function, as aldosterone's primary effect is actually to conserve water and sodium, thereby increasing blood volume.