The concentration of which electrolyte is directly regulated by aldosterone?

Correct option is C

Ans. (c) Sol. Aldosterone primarily regulates the concentration of sodium (Na⁺) in the body. It is a hormone secreted by the adrenal cortex as part of the renin-angiotensin-aldosterone system (RAAS). Aldosterone acts on the kidneys (distal tubules and collecting ducts) to increase sodium reabsorption while promoting potassium (K⁺) and hydrogen (H⁺) excretion. This regulation helps maintain blood pressure, fluid balance, and electrolyte homeostasis.
Explanation of Other Options:
· (a) Calcium: Regulated primarily by parathyroid hormone (PTH), vitamin D, and calcitonin, not aldosterone.
· (b) Iron: Regulated by hepcidin, not aldosterone.
· (d) Magnesium: Controlled mainly by kidney function and PTH, but not directly regulated by aldosterone.