Growth hormone and hypophosphatemic rickets.

This review summarizes seven trials of growth hormone (GH) treatment for X-linked hypophosphatemic rickets (XLHR). These trials range in size from 5 to 30 patients; but despite the limited number of patients enrolled, they represent the largest studies to date of growth hormone in this disorder. Conventional treatment in XLHR, oral phosphate and calcitriol, is often unable to normalize serum phosphate concentration fully and many patients fail to reach normal adult height. The studies reviewed report increased growth velocity when exogenous GH is added to conventional therapy, although the independent effect of GH is difficult to evaluate. Younger patients appear to respond better to GH than do older patients. Disproportionate growth of the trunk may be a problem. Some patients with XLHR have received GH for more than 6 years, yet little is known about the impact of GH on adult height. Reported increases in phosphate concentrations following GH in XLHR are of uncertain clinical benefit. While GH appears to be safe in XLHR, long-term benefits remain unclear.