aldosterone. [al′dōstərōn′, aldos′tərōn]. a mineralocorticoid steroid hormone produced by the adrenal cortex with action in the renal tubule to retain sodium, conserve water by reabsorption, and increase urinary excretion of potassium.ldosterone. A hormone secreted by the adrenal glands that is important for maintaining salt and water balance in the body. Mentioned in: Congenital Adrenal Hyperplasia. hormone secreted by the adrenal glands, at a rate regulated by the level of sodium in body fluids.