[Fractional composition of serum calcium in chronic heart failure]

The total calcium concentration (Cat) using an atom-absorption spectrophotometer and ionized calcium concentration (Ca2+) with ionoselective electrodes were determined in the blood serum of 28 healthy persons and 159 patients with chronic cardiac insufficiency (CCI). The blood serum Cat concentration in CCI decreased clearly in parallel with its gravity. Ca2+ concentration remained within normal fluctuations shifting to their low border ("hypocalcemia within normal"). These shifts of the calciemia fractional composition were determined by a decrease in the calcium-binding capacity (CBC) of serum buffers resulting in a decreased portion of the physiologically inert nonionized (bound) fraction in Cat. Cat concentration grows with the effective treatment of CCI, perhaps as a result of the normalization of CBC.