A trial of growth hormone therapy in well-controlled hypophosphataemic rickets.

Abstract

Conventional therapy of hypophosphataemic rickets (HR) with oral phosphate and calcitriol does not always result in normal linear growth. Recombinant human growth hormone (rhGH) offers theoretical advantages as an adjunctive therapy. We aimed to determine the effects of adjunctive rhGH therapy in children with well-controlled HR. In this report, 5 prepubertal children (aged 3.5-10.9 years) with well-controlled HR on conventional therapy were given adjunctive standard dose rhGH therapy for one year. Height, growth velocity, metabolic markers of calcium and phosphate metabolism, body composition, bone mineral density, wrist and knee X-rays, and renal sonography were assessed at regular intervals. Height and growth velocities were also calculated 12 months after ceasing rhGH therapy. After 12 months therapy with rhGH, no significant biochemical or radiological benefits were observed. A significant increase in height SD score was observed (P = 0.023), but this was not associated with any increase in the growth velocity SD score and appears to have been due to catch-up growth caused by conventional therapy alone. When rhGH therapy was ceased, no significant decreases in mean height SD or growth velocity SD scores were observed. In well-controlled hypophosphataemic rickets patients receiving conventional therapy, adjunctive therapy with standard dose rhGH offers no benefits in linear growth or rachitic disease markers.