Aldosterone primarily regulates which of the following?

• A. Sodium and water levels
• B. Blood glucose
• C. Immune response
• D. Bone density

Answer: (A)

Aldosterone mainly controls sodium and water balance in the body. It acts on the kidneys, specifically the distal tubules and collecting ducts, to increase sodium reabsorption. Water follows sodium by osmosis, so this reabsorption raises blood volume and helps regulate blood pressure. It also promotes potassium excretion. This hormone is released as part of the renin-angiotensin-aldosterone system, which responds to low blood pressure or low sodium. Because its primary role is electrolyte and fluid regulation, it does not directly regulate blood glucose, the immune response, or bone density.