Aldosterone is produced by multiple hydroxylations of deoxycorticosterone and is normally 60% protein bound. The renin-angiotensin system stimulates aldosterone release. Increased potassium stimulates aldosterone production, and decreased potassium inhibits production. Chronic adrenocorticotropic hormone (ACTH) deficiency may inhibit production.
The primary actions of aldosterone cause the kidneys, gut, and salivary/sweat glands to affect electrolyte balance. The primary targets are the kidneys; where it stimulates reabsorption of sodium and secretion of potassium and hydrogen ions. The kidneys' effect on sodium and potassium depend on the intake of these cations (ie, increased sodium intake = increased potassium secretion). The effects on hydrogen probably can occur independently.
Persistent aldosterone excess results in atrial natriuretic factor release and renal hemodynamic changes for compensation. Congestive heart failure (CHF) and cirrhosis with ascites are exceptions that cause progressive sodium retention. Excess aldosterone results in sodium retention, hypokalemia, and alkalosis. Aldosterone deficiency results in sodium loss, hyperkalemia, and acidosis. Hyperkalemia stimulates aldosterone release to improve potassium excretion. Aldosterone is the first-line defense against hyperkalemia.
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Regulation of the adrenal cortex.
