Which mineralocorticoid regulates sodium and water levels in the body?

• A. Cortisol
• B. Aldosterone
• C. Androgen
• D. Insulin

Answer: (B)

The essential idea is how the body controls sodium and water balance through a mineralocorticoid. Aldosterone, produced by the adrenal cortex, acts on the kidney’s distal tubules and collecting ducts to increase sodium reabsorption. As sodium is reabsorbed, water follows, raising blood volume and helping to regulate blood pressure and electrolyte balance. This hormone is regulated by the renin-angiotensin-aldosterone system, especially when blood pressure or sodium levels drop or potassium rises. The other options aren’t the main minerals controlling this balance: cortisol is a glucocorticoid mainly involved in metabolism and stress response (with only a minor mineralocorticoid effect), androgen is a sex hormone, and insulin controls glucose metabolism. Therefore, aldosterone is the mineralocorticoid that regulates sodium and water levels.