[Calciuretic function of the kidneys in chronic cardiac insufficiency]

Excretion of calcium (Eca) with the kidneys decreases parallel with progress of chronic heart insufficiency (CHI). In stage III CHI, the daily Eca constitutes 25.4% on the average of normal. The reduction in calciuresis is about to an equal extent determined by hemodynamic disorders, drop of glomerular filtration, and increase of tubular calcium reabsorption. Inhibition of tubular calcium reabsorption is the decisive factor that determines the degree of the calciuretic response after oral intake of calcium lactate. Insufficient inhibition of tubular calcium transport, as compared to controls, accounts for a decrease in the calciuretic response to the intake of calcium lactate in patients with CHI. It is assumed that the increased tubular calcium reabsorption is caused by the action of some extrarenal regulatory factors that reduce the ability of CHI patients to resist external excess calcium supply.