[Assessment of the calcium homeostatic state using the double calcium tolerance test]

An acute tolerance test per os using calcium (Ca) lactate at a dose of 0.25 mmol of Ca per kg of body mass (calcium tolerance test--CTT) was performed twice in healthy persons (HP) and in patients with chronic heart failure (CHF) of various degrees: before and after 3-day administration of the same dose of Ca lactate. The "double" CTT made it possible to detect in HP and CHF a "phenomenon of adaptation" to Ca excess in the body based probably on changes in the activity of calcium-regulating hormones. It was manifested in less marked and prolonged tolerance hypercalcemia and a more rapid and effective calciuretic reaction, and probably in decreased intestinal absorption of Ca. It pointed to reversibility of Ca metabolic derangements even in severe CHF and a possibility of their non-medicamentous correction.