Monday, May 31, 2010

What is Aldosterone?

A hormone of the adrenal glands responsible for regulating SODIUM in the blood. It is classified as a corticosteroid, a group of hormones synthesized by the adrenal cortex. Aldosterone is the principal MINERALOCORTICOID, which directs the KIDNEYS to conserve SODIUM by reabsorbing sodium and water from urine. In the kidneys, aldosterone stimulates the renal tubules to release POTASSIUM and hydrogen ions in place of sodium, thus increasing urine acidity. Mineralocorticoids also increase sodium reabsorption from sweat, SALIVA, and GASTRIC JUICES. Other steroid hormones, deoxycorticosterone, corticosterone, and progesterone, can also cause sodium retention, though they are much less active.
Stimuli that increase aldosterone secretion include SURGERY, anxiety, physical trauma, high potassium intake, low sodium intake, and diseases of the heart, LIVER, and kidneys. The pituitary hormone ACTH stimulates steroid hormone release from the adrenal glands. Aldosterone is also regulated by the kidneys in response to low serum sodium levels. The kidneys produce an enzyme, RENIN, which forms the hormone ANGIOTENSIN in the blood that stimulates aldosterone release.

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