What is the primary role of aldosterone in the body?

• A. Regulates potassium excretion
• B. Regulates sodium reabsorption in renal tubules
• C. Regulates blood glucose levels
• D. Regulates metabolism of fats

Answer: (B)

Aldosterone primarily functions to regulate sodium reabsorption in the renal tubules. It is a steroid hormone produced by the adrenal cortex and plays a key role in maintaining fluid and electrolyte balance in the body. When aldosterone is secreted, it acts on the cells in the distal convoluted tubule and collecting duct of the nephron, promoting the reabsorption of sodium ions back into the bloodstream. This process not only helps to increase sodium levels but also encourages water retention, thereby influencing blood volume and blood pressure.

Furthermore, aldosterone indirectly affects potassium levels by promoting its excretion in exchange for sodium reabsorption. While potassium excretion is an important function of aldosterone, the primary role lies in sodium regulation. The hormone does not have a primary role in the regulation of blood glucose levels or the metabolism of fats, which are controlled by other hormones such as insulin and glucagon for glucose and various hormones or cofactors for fat metabolism.