Recombinant Human GH Replacement Therapy in Children with Pseudohypoparathyroidism Type Ia: First Study on the Effect on Growth

Abstract

Since the identification of GH deficiency due to resistance to GHRH in patients with pseudohypoparathyroidism type Ia (PHP-Ia), no study investigated the effects of recombinant human GH (rhGH) therapy on height velocity (HV) in these patients. To address this question, eight prepubertal PHP-Ia children with GH deficiency (seven girls and one boy, aged 5.8-12 yr) underwent a 3- to 8-yr treatment with rhGH. Height and HV were measured before and at 6-month intervals during therapy. Nine sex- and age-matched children with idiopathic GH deficiency were monitored during rhGH therapy for comparison. In PHP-Ia children, height sd scores increased from -2.4 ± 0.58 to -1.8 ± 0.47 (P = 0.04) after 12 months, this increase being maintained after the second (-1.6 ± 0.6) and third (-1.15 ± 0.6) year of therapy, similarly to what recorded in children with idiopathic GH deficiency. The HV and HV sd scores after 3 yr maintained a significant increase from 3.5 ± 0.6 to 7.0 ± 0.9 cm/yr (P < 0.0001) and from -2.8 ± 0.8 to +2.2 ± 1.0 (P < 0.0001), respectively. Six patients treated for 4-8 yr had a reduced pubertal spurt and did not improve their near-adult height, with the only exception of one patient in whom estrogen production was blocked by GnRH analogs. We report the first study on the efficacy of rhGH replacement therapy in prepubertal children with PHP-Ia and provide indication that treatment of GH deficiency should be started soon due to the rather limited time window for a potentially effective therapy.