Growth hormone therapy in a poorly growing child with hypophosphatemic rickets.

We treated a 10 6/12 year old prepubertal male with hypophosphatemic rickets, who was growing poorly despite appropriate treatment with calcitriol and phosphate, with exogenous growth hormone (for an initial trial period of 4 months, followed by 14 months of continuous treatment at a dose of 4 IU three times weekly) even though his growth hormone testing proved to be normal. His growth rate increased significantly during treatment with synthetic growth hormone (from a basal rate of 3.9 cm/yr to 9 cm/yr during the first 4 months of therapy and from 2.7 cm/yr to 6.0 cm/yr during next 14 months of treatment) and his predicted adult height increased as well. Slight metabolic changes were detected in this patient during treatment, with an increase in serum phosphorus and a decrease in twenty-four hour urine calcium concentrations. It would seem reasonable to evaluate the growth hormone status of children with hypophosphatemic rickets who are growing poorly despite appropriate therapy with calcitriol and phosphate and to consider a trial period of therapy with growth hormone in some of them.