Aldosterone

Aldosterone is a mineralocorticoid produced in the adrenal cortex. Aldosterone production can be triggered by Angiotensin II (i.e. by hypotension) or directly by the presence of excess serum potassium.

The primary role of aldosterone is to maintain ECF volume by promoting the reabsorption of sodium (balanced by the excretion of potassium) from the renal tubule into the ECF. This forces the reabsorption of water from the renal tubule via osmosis, increasing ECF volume.