The Beneficial Effect of Combined GH/GnRHa Therapy in Increasing Adult Height Outcome in Children With ISS.

Context: Management of GH-treated children with idiopathic short stature (ISS) with early puberty and adolescents in midpuberty at initiation of treatment is challenging.

Objective: To assess the effect of combined GH/GnRHa therapy during puberty on achieved adult height (AHt) in these children with ISS and to determine whether outcome depended on sex and pubertal status at initiation of GH therapy.

Design: Retrospective, single-center observational study from 2003-2018.

Setting: Tertiary endocrine center.

Patients: One hundred ninety-two GH-treated children with ISS; 58 of 192 were treated by GH/GnRHa during puberty; 31 of 58 were prepubertal (19 girls) and 27 of 58 pubertal (19 girls) at initiation of GH.

Main Outcome Measures: AHt, gain-in-height standard deviation score (SDS), AHt vs predicted adult height (PAHt), AHt vs target height (THt).

Results: Most boys and girls attained AHt SDS within the normal range (-0.73 ± 0.60 and -0.85 ± 0.65, respectively). Treatment modality, pubertal status, and sex were tested for their joint effect on growth outcome measures. Combined GH/GnRHa therapy increased AHt vs PAHt (P < 0.001) and AHt vs THt (P = 0.035). Prepubertal status at onset of GH treatment increased AHt (P = 0.049), gain-in-height SDS (P < 0.001), AHt vs PAHt (P < 0.001), and AHt vs THt (P = 0.042). Female sex increased AHt vs PAHt (P < 0.001).

Conclusions: Our study demonstrated a beneficial effect of combined GH/GnRHa therapy in increasing AHt outcome in children with ISS with early/normal puberty and in adolescents naïve to GH treatment who are in midpuberty at initiation of therapy. This effect was more pronounced in the prepubertal group and in girls. Prospective randomized controlled trials are needed to assess whether GnRHa can increase AHt in GH-treated children with ISS.