Two-year recombinant human growth hormone (rhGH) treatment is more effective in pre-pubertal compared to pubertal short children with X-linked hypophosphatemic rickets (XLHR)

Abstract

ContextTwenty-five to 40% of patients with well-controlled X-linked hypophosphatemic rickets (XLHR) have a final height under −2 SDS. Previous studies have shown that recombinant human growth hormone (rhGH) treatment improves linear growth in short children with XLHR. ObjectiveWe studied the effectiveness of rhGH treatment in children with XLHR in a larger cohort. DesignMonocentric, prospective, non-randomized trial. SettingUniversity hospital in France. Patients19 patients with XLHR and a mutation in the PHEX gene. Six male and 6 female Tanner stage 1 patients (age 6.1±2.4years) and 4 male and 3 female Tanner stage 2 patients (age 13.1±1years). At inclusion, height SDS was −2.35±0.8 SDS and growth velocity was −1.12±1.2 SDS. Intervention2years of treatment with 67mcg/kg/day of rhGH at initiation. Every three months rhGH dosage was adjusted using an IGF-1 dosing protocol. Main outcome measuresComparison in change from baseline to year 2 in height and growth velocity. ResultsHeight SDS improved from −2.35±0.8 SDS at baseline, to −1.62±0.8 SDS (p=0.01) after one and to −1.2±1 SDS (p=0.04) after two years of rhGH treatment. There was a strong correlation (r2=0.6104, p<0.0001) between the age of onset of rhGH treatment and the number of cm gained over the study period. Pre-pubertal patients height SDS improved compared to baseline height SDS after one (−1.5±0.7, p<0.03) and two (−0.96±1, p<0.03) years of rhGH treatment. In pubertal patients there was no significant improvement in height SDS after one year (−1.75±1) and after two years (−1.7±0.8) of rhGH treatment. ConclusionTwo-year rhGH treatment is effective to treat short stature in XLHR children. Pre-pubertal children responded better to rhGH. Clinical trial registration numberNCT02720770