Rothenbuhler A, et al. – The effectiveness of recombinant human growth hormone (rhGH) treatment was examined in children with X–linked hypophosphatemic rickets (XLHR). Results confirmed that 2–year rhGH treatment was effective to treat short stature in XLHR children. Moreover, pre–pubertal children responded better to rhGH.

Methods

• This study consisted of 19 patients with XLHR and a mutation in the PHEX gene.
• Six male and 6 female Tanner stage 1 patients (age 6.1 ± 2.4 years) and 4 male and 3 female Tanner stage 2 patients (age 13.1 ± 1 years).
• At inclusion, height SDS was –2.35 ± 0.8 SDS and growth velocity was –1.12 ± 1.2 SDS.
• 2 years of treatment with 67 mcg/kg/day of rhGH at initiation.
• With an IGF–1 dosing protocol, every three months rhGH dosage was adjusted.
• Comparison in change from baseline to year 2 in height and growth velocity.

Results

• Height 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.
• Findings indicated 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.
• After one year (–1.75 ± 1) and after two years (–1.7 ± 0.8) of rhGH treatment, no significant improvement was observed in height SDS, in pubertal patients.