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

Abstract

Objective: To evaluate the effect of growth hormone treatment on final height, phosphate metabolism, bone markers, and bone mineral density in children with X-linked hypophosphatemic rickets. Study Design: Six patients (aged 7.8 ± 1.8 years; height z score, –3.4 ± 0.5) received conventional treatment (1,25-dihydroxyvitamin D3 plus phosphate salts) combined with growth hormone (0.6-0.9 IU/kg per week, subcutaneously) (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 treatment (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 in group B (–2.8 ± 0.5, P = NS). At final height, degree of body disproportion 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 density increased only in group A. No adverse effects were observed. Conclusions: In poorly growing patients with X-linked hypophosphatemic rickets, growth hormone therapy combined with conventional treatment improves final height, phosphate retention, and radial bone mineral density, but it does not influence degree of body disproportion. (J Pediatr 2001;138:236-43)