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

Abstract

Divalent ion metabolism in patients with acute renal failure: Studies on the mechanism of hypocalcemia. Studies were carried out in ten 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 three 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. Metabolisme des ions divalents chez les malades atteints d'insuffisance renale aigue: Etude du mecanisme de l'hypocalcemie. Dix malades atteints d'insuffisance renale aigue ont ete etudies afin de caracteriser certains aspects de l'alteration du metabolisme des ions divalents. Au cours de la periode oligurique il existe une hypocalcemie, une hyperphosphatemie, une hypermagnesemie et des concentrations elevees d'hormone parathyroidienne immunoreactive. L'hypocalcemie et l'augmentation de la concentration d'hormone parathyroidienne immunoreactive persistent au cours de la phase diuretique alors que le phosphate et le magnesium plasmatiques sont souvent inferieurs aux valeurs normales. Aucune correlation n'a ete trouvee entre les concentrations plasmatiques de calcium et de magnesium alors qu'une correlation inverse existait entre la concentration d'hormone parathyroidienne immunoreactive et la concentration plasmatique du calcium. La concentration du calcium ionise est basse et la fraction du calcium total liee aux proteines est normale. La perfusion d'extrait parathyroidien au cours des phases oligurique et diuretique n'induit pas l'augmentation normalement attendue de la concentration du calcium plasmatique. Apres le retour a la normale de la fonction renale, la reponse a l'extrait parathyroidien devient normale. La resistance a l'action hypercalcemiante de l'extrait parathyroidien perfuse a ete observee aussi apres trois jours d'uremie aigue chez des chiens thyroparathyroidectomises. Ces travaux montrent que l'hypocalcemie et l'hyperparathyroidisme secondaire surviennent precocement au cours du deroulement de l'insuffisance renale aigue et les resultats indiquent que la resistance a l'action osseuse de l'hormone parathyroidienne joue un role important dans la genese de ces anomalies.