Divalent ion metabolism in patients with acute renal failure: Studies on the mechanism of hypocalcemia

Abstract

Studies were carried out in 10 patients with acute renal failure to characterize certain features of deranged divalent ion metabolism. During the oliguric period, the patients displayed hypocalcemia, hyperphosphatemia, hypermagnesemia and elevated levels of immunoreactive parathyroid hormone. Hypocalcemia and elevated levels of immunoreactive parathyroid hormone persisted into the diuretic phase while serum phosphorus and magnesium often fell to or below normal. No correlation was found between concentrations of serum calcium and phosphorus, while there was an inverse correlation between those of immunoreactive parathyroid hormone and serum calcium. The concentrations of ionized calcium were low, and the percent of total calcium bound to protein was normal. The infusion of parathyroid extract during the oliguric and diuretic phases failed to elicit a normal rise in serum calcium concentration. When renal function had returned to normal, serum calcium and phosphorus values and the response to the infusion of parathyroid extract were normal. Resistance to the calcemic action of infused parathyroid extract was also found in thyroparathyroidectomized dogs after 3 days of acute uremia. These studies demonstrate that hypocalcemia and secondary hyperparathyroidism occur early in the course of acute renal failure, and the results indicate that resistance to the skeletal action of parathyroid hormone plays an important role in the genesis of these abnormalities.