[Role of the parathyroid glands in the genesis of hypocalcemia in myocardial infarct].

Plasma levels of immunoreactive parathyroid hormone and total as well as ionized calcium were measured in 18 patients with myocardial infarction on days 7 and 20-25 of the disease. An experimental study in 90 white rats was designed to determine bodily requirement of parathyroid hormone and specify its role in the genesis of hypocalcemia. On day 7 of acute myocardial infarction, the patients showed decreased plasma levels of total and ionized calcium, and their parathyroid hormone levels dropped simultaneously. The experimental study in parathyroidectomized rats with simulated myocardial infarction demonstrated that the hormone requirement grew during the acute stage of infarction. On days 20-25, the myocardial infarction patients showed an increase in total and ionized calcium, yet their parathyroid hormone levels continued to decline, a fact attributable to functional exhaustion of the parathyroid glands.