Hypoaldosteronism, abnormally low serum levels of aldosterone, a steroid hormone secreted by the adrenal gland. Hypoaldosteronism nearly always arises as a result of disorders in which the adrenal glands are destroyed. However, there does exist a disease in which defective aldosterone synthesis and secretion from the zona glomerulosa in the adrenal gland occur in the presence of otherwise normal adrenocortical function.
Isolated aldosterone deficiency results in low serum sodium concentrations (hyponatremia), decreased extracellular (including plasma) volume, and high serum potassium concentrations (hyperkalemia). These biochemical changes cause weakness, postural hypotension (a decrease in blood pressure upon standing), salt craving, and heart block, which may be fatal. Hypoaldosteronism is often associated with mild to moderate kidney disease, especially in patients with diabetes mellitus. Under normal circumstances, the kidneys secrete an enzyme known as renin, which acts on a substance in the blood called angiotensinogen to produce angiotensin II, a peptide that stimulates aldosterone secretion from the adrenal gland. However, in patients with diabetes mellitus, hypoaldosteronism is caused by deficient production of renin by the kidneys that leads to decreased production of angiotensin II and therefore decreased secretion of aldosterone.
Other causes of hypoaldosteronism are rare and are primarily the result of enzymatic defects in the synthesis of aldosterone and resistance of the kidneys to the actions of aldosterone. In patients with hypoaldosteronism from these causes, renin production by the kidneys is increased. Treatment of hypoaldosteronism consists of the administration of salt or a potent synthetic mineralocorticoid such as fluorohydrocortisone (fludrocortisone). Orally administered aldosterone is ineffective because it is poorly absorbed by the body.
Learn More in these related Britannica articles:
Aldosterone, a steroid hormone secreted by the adrenal glands. Aldosterone serves as the principal regulator of the salt and water balance of the body and thus is categorized as a mineralocorticoid. It also has a small effect on the metabolism of fats, carbohydrates, and proteins.…
Steroid hormone, any of a group of hormones that belong to the class of chemical compounds known as steroids; they are secreted by three “steroid glands”—the adrenal cortex, testes, and ovaries—and during pregnancy by the placenta. All steroid hormones are derived from cholesterol. They are transported through the bloodstream to…
Adrenal gland, either of two small triangular endocrine glands one of which is located above each kidney. In humans each adrenal gland weighs about 5 grams (0.18 ounce) and measures about 30 mm (1.2 inches) wide, 50 mm (2 inches) long, and 10 mm (0.4 inch)…
Heart block, lack of synchronization in the contractions of the upper and the lower chambers of the heart—the atria and the ventricles. The lack of synchronization may range from a slight delay in the ventricular contractions to total heart block, a complete lack of synchronization between the atria and the…
renal system disease: Diseases and disorders of the kidneyIn this section, attention is directed not only to specific diseases of the kidney but also to the syndromes of acute and chronic renal failure, which have multiple causes. Infective disorders of the kidney are dealt with later, as part of the general problem…