Which hormone regulates sodium retention and potassium excretion?

Aldosterone is the hormone responsible for regulating sodium retention and potassium excretion. It is produced by the adrenal cortex and plays a critical role in maintaining electrolyte balance and blood pressure. Aldosterone acts primarily on the kidneys, promoting the reabsorption of sodium back into the bloodstream while facilitating the excretion of potassium into the urine. This process helps to increase blood volume and, consequently, blood pressure, as sodium reabsorption leads to water retention.

The regulation of sodium and potassium by aldosterone is part of a larger system called the renin-angiotensin-aldosterone system (RAAS), which is activated in response to low blood pressure or low sodium levels. In summary, aldosterone's specific actions on sodium and potassium make it the key hormone in the regulation of these electrolytes.