Complex biochemical syndrome of hypocalcemia and hypoparathyroidism during cytotoxic treatment of an infant with leukemia.

Patients with cancer are especially vulnerable to the development of hyper- and hypocalcemia. These disorders may be the basic clinical manifestation of cancer or may result from vigorous cancer treatment. During cytotoxic treatment of a child with leukemia we describe the longitudinal course of ionized calcium in a complex syndrome of hypocalcemia and hypoparathyroidism. The results suggest that the development of severe hypocalcemia can be explained on the basis of hypoparathyroidism in relation to hyperphosphatemia, hypomagnesemia, and acute renal failure. The low ionized calcium was unsuccessfully treated with several doses of calcium levulinate but successfully treated with 1 alpha-hydroxycholecalciferol.