Aldosterone is a steroid hormone, it is synthesized from cholesterol in the cells of the glomerular layer of the adrenal cortex. This is the main and most potent mineralocorticoid. Metabolized in the liver and kidneys, causes an increase in the reabsorption of sodium and chlorine in the renal tubules. As a result, sodium and chlorine retention in the body is observed, a decrease in the release of fluid in the urine, in parallel, there is an increase in the excretion of potassium. Aldosterone is involved in the regulation of electrolyte balance, maintenance of blood volume and blood pressure. Normal secretion of aldosterone depends on many factors - the activity of the renin-angiotensin system, potassium content (hyperkalaemia stimulates, and hypokalemia suppresses aldosterone production), ACTH (a short-term increase in aldosterone secretion under physiological conditions is not the main factor in the regulation of secretion), magnesium and sodium in the blood. Excess aldosterone causes hypokalemia, metabolic alkalosis, a noticeable sodium retention and increased urinary potassium excretion, which is clinically manifested by hypertension, muscle weakness, seizures and paresthesia, and arrhythmias. With primary hyperaldosteronism (Connes syndrome), an autonomous increase in the secretion of aldosterone is observed, the cause of which is most often adenoma of the glomerular zone of the adrenal cortex (up to 62% of all observations). Secondary hyperaldosteronism is associated with congestive heart failure, cirrhosis with the formation of ascites, certain kidney diseases, excess potassium, low-sodium diet, toxicosis of pregnant women, stenosis of the renal arteries (2-3% of all cases of hypertension). Primary hyperaldosteronism is characterized by an increase in the level of aldosterone, combined with a low activity of plasma renin, for secondary hyperaldosteronism - an increase in aldosterone concentration is combined with a high plasma renin activity. Hypoaldosteronism is usually accompanied by hyponatremia, hyperkalemia, a decrease in the excretion of potassium in the urine and an increase in the excretion of sodium, metabolic acidosis and hypotension. The most common cause of this condition is decreased production of renin due to kidney damage (giporeninemic hypoaldosteronism), especially in diabetics. Chronic insufficiency of the adrenal cortex (Addison's disease) due to its primary damage in tuberculosis, autoimmune pathology of the adrenal gland, amyloidosis is accompanied by a decrease in the level of aldosterone and an increase in plasma renin level. Before determining aldosterone, the patient should be transferred to medications with minimal effect on the level of the hormone.