Parathyroid hormone and 25-hydroxycholecalciferol levels in hypercalcemia of acute renal failure.

A 38-year-old man developed symptomatic hypercalcemia during the diuretic phase of acute renal failure secondary to rhabdomyolysis. Although early secondary hyperparathyroidism was documented, parathyroid hormone levels fell when hypercalcemia occurred. The 25-hydroxycholecalciferol level was normal on two separate occasions during the hypercalcemia. Remobilization of muscle calcium deposits during diuresis is proposed as the cause of the hypercalcemia in this syndrome.