THE HYPERCALCEMIA OF ADRENAL INSUFFICIENCY*

Abstract

Hypercalcemia occurred as frequently as hypo-natremia in adrenalectomized dogs, and was considerably more pronounced. In patients with Addison''s disease, hypercalcemia appears to be somewhat less frequent, but adequate data are lacking. In adrenalectomized rats, it did not occur at all, even when they were fed a high-calcium, low-sodium diet. In dogs, hypercalcemia may be severe, but the concentration of free calcium ions was normal. Plasma Mg was usually reduced. Three alterations in the plasma combined to produce hypercalcemia: the elevated plasma protein concentration associated with hemoconcentration; an increase in filtrable calcium complexes; and an increase in the affinity of protein for calcium. The last could be explained in part as a consequence of hyponatremia and the resulting reduction in the ionic strength of plasma, and in part as a result of excessive amounts of a nonfiltrable compound of calcium and phosphate, formed either in vivo, in vitro, or both. The increased calcium concentration of plasma was not dependent upon increased intestinal absorption since it also occurred on a calcium free diet.