mineralocorticoid

any of a group of hormones elaborated by the cortex of the adrenal gland, so called because of their effects on sodium, chloride, and potassium concentrations in the extracellular fluid. They are the adrenocortical hormones that are essential to the maintenance of adequate fluid volume in the extracellular and intravascular fluid compartments, normal cardiac output, and adequate levels of blood pressure. Without sufficient supply of the mineralocorticoids, fatal shock from diminished cardiac output can occur very quickly.

The principal mineralocorticoid is aldosterone, which accounts for most of the activities of this group of hormones. The primary effects of the mineralocorticoids are increasing the reabsorption of sodium and the secretion of potassium in the renal tubules. Secondary effects are related to the reabsorption of water, serum levels of sodium and potassium, anion reabsorption, and secretion of hydrogen ions. The net result of these activities is maintenance of fluid and electrolyte balance and, therefore, adequate cardiac output.