The hope that arresting pubertal developement might increase final adult height has led to an attempt to use GnRH agonist (GnRHa) in children with early puberty and poor growth prognosis. We investigated the growth-promoting effect of GnRH agonists with or without growth hormone (GH) in girls with early puberty and decreased predicted adult height (PAH).

Thirty five girls with advanced bone age and early pubertal signs were randomized for treatment for about 1 year with monthly GnRHa in group 1 (n=18), or with a combination of GH and GnRHa in group 2 (n=17). The following growth parameters were compared between groups, and the difference (Δ) before and after treatment : chronological age (CA), bone age (BA), Δ(BA-CA), height (HT), target height (TH), predicted adult height (PAH), Δ(TH-PAH), serum insulin-like growth factor (IGF-1) and insulin-like growth factor binding protein (IGFBP-3).

Before treatment, BA, TH, PAH Standard deviation scores (SDS), Δ(TH-PAH) were not different between the two groups, but CA was higher in group 2 and Δ(BA-CA) were higher in group 1 ( P <0.05). After 1.06±0.93 year of treatment, Δ(BA-CA) decreased and there were significant changes in PAH and Δ(TH-PAH), especially in group 2 ( P <0.05 in group 1, and P <0.001 in group 2). In both groups, IGF-1 and IGFBP-3 were not different before and after treatment, but after treatment, IGF-1 level in group 2 was marginally higher than IGF-1 in group 1 ( P <0.1).

Compromised predicted adult height in girls with early puberty and advanced bone age was significantly improved with GnRH with/without GH treatment in the short-term period. The addition of GH to GnRHa results in a significant increase in PAH compared to GnRHa alone because GnRHa suppressed growth hormone-IGF-1 axis. For comparison of final adult height, further longitudinal follow-up will be needed.