The article pathogenetically substantiates the feasibility of using methods for determining functional renal reserve through salt and water loading of 0.5% sodium chloride in an amount of 0.5 % of the body weight in patients suffering from chronic kidney disease. The informative value of determining the functional renal reserve in clinical nephrology on the example of patients with essential hypertension, diabetes mellitus, and AIDS is shown when assessing the nature and extent of nephron damage.
