Serum parathyroid hormone in hypophosphatemic vitamin D-resistant rickets.

Serum parathyroid hormone (PTH) was measured in five children with untreated, active hypophosphatemic vitamin D-resistant rickets be[ore, during, and after an in[usion o[ calcium. During the calcium in[usion, serum PTH decreased while the tubular resorption of phosphate increased. Although these data clearly indicate that some degree o[ hyperparathyroidism accompanies the disease, it is apparent that the degree o[ hyperparathyroidism recorded in these studies is not sufficient to explain the severity o[ the phosphaturia. One o[ the basic dejects in the disease may involve excessive sensitivity o[ the renal tubule to the phosphaturie effects o[ PTH.