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

OBJECTIVE Conventional therapy of hypophosphataemic rickets (HR) with oral phosphate and calcitriol does not always result in normal linear growth. Re combinant human growth hormone (rhGH) offers theoretical advantages as an a djunctive therapy. We aimed to determine the effects of adjunctive rhGH the rapy in children with well-controlled HR, PATIENTS In this report, 5 prepub ertal children (aged 3.5-10.9 years) with well-controlled HR on conventiona l therapy were given adjunctive standard dose rhGH therapy for one year. DESIGN AND MEASUREMENTS Height, growth velocity, metabolic markers of calci um and phosphate metabolism, body composition, bone mineral density, wrist and knee X-rays, and renal sonography were assessed at regular intervals. H eight and growth velocities were also calculated 12 months after ceasing rh GH therapy. RESULTS After 12 months therapy with rhGH, no significant biochemical or ra diological benefits were observed. A significant increase in height SD scor e 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 growt h caused by conventional therapy alone. When rhGH therapy was ceased, no si gnificant decreases in mean height SD or growth velocity SD scores were obs erved. CONCLUSIONS 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.