Aldosterone, the predominant mineralocorticoid, is secreted by the zona glomerulosa of the adrenal cortex in response to decreased serum sodium, decreased blood volume, and increased serum potassium. It is thought that altered serum sodium and potassium levels directly stimulate the adrenal cortex to release aldosterone. In addition, decreased blood volume and altered sodium and potassium levels stimulate the juxtaglomerular apparatus of the kidney to secrete renin. Renin is subsequently converted to angiotensin II, which then stimulates the adrenal cortex to secrete aldosterone. In normal states, ACTH does not play a major role in aldosterone secretion. In disease or stress states, however, ACTH may also enhance aldosterone secretion.

Aldosterone increases sodium reabsorption in the renal tubules, gastrointestinal tract, salivary glands, and sweat glands. This subsequently results in increased water retention, blood volume, and blood pressure. Aldosterone also increases potassium excretion by the kidneys in exchange for the sodium ions that are retained.