Effect of growth hormone treatment on final height, phosphate metabolism, and bone mineral density in children with X-linked hypophosphatemic rickets

Objective: To evaluate the effect of growth hormone treatment on final heig ht, phosphate metabolism, bone markers, and bone mineral density in childre n with X-linked hypophosphatemic rickets. Study design: Six patients (aged 7.8 +/- 1.8 years; height,- score, 3.4 +/- 0.5) received conventional treatment (1,25-dihydroxyvitamin D-3 plus phosp hate salts) combined with growth hormone (0.6-0.9 IU/kg per week, subcutane ously) (group A); 6 patients (aged 7.9 +/- 2.5 years; height z score, -2.1 +/- 0.6, P <.01 with respect to group A) received only conventional treatme nt (group B). Results: Final height z score significantly improved in group A (-2.4 +/- 0 .5, P <.03 with respect to the value at entry), whereas it did not change i n group B (-2.8 +/- 0.5, P = NS). At final height, degree of body dispropor tion was similar between the groups (group A, 1.3 +/- 0.2; group B, 1.2 +/- 0.1; P = NS). Phosphate retention, bone markers, and radial bone mineral d ensity increased only in group A. No adverse effects were observed. Conclusions: In poorly growing patients with X-linked hypophosphatemic rick ets, growth hormone therapy combined with conventional treatment improves f inal height, phosphate retention, and radial bone mineral density, but it d oes not influence degree of body disproportion.