A pilot study of growth hormone administration in boys with predicted adult short stature and near-ending growth

Abstract

ContextThe growth-promoting effect of starting recombinant human growth hormone (rhGH) at the time of near-ending growth has not been studied in sexually mature boys who will have idiopathic short stature (ISS) as adults because it is believed that such an advanced stage of puberty would preclude favorable results. Objectives1) To explore the effects of starting rhGH administration at time of near-ending growth in boys with ISS. 2) To search for predictors of response to rhGH. SubjectsFifteen boys aged 15.5±1years terminating puberty were growing at a rate <2cm/6months towards a predicted adult height (PAH) <−2.5 SDS. MethodsParticipants received 0.50±0.06mg/kg·wk of rhGH according to a target-to-treat protocol. When growth became less than 0.5cm in 3months or when height has reached 169cm, rhGH was ceased. Testosterone, growth velocity (GV), height, serum IGF-1, bone age (BA) at hand–wrist and knee score were measured at onset; IGF-1 and height were monitored every 3months. A formula for PAH was developed. Height increment (HI, adult height-starting height) and height gain (HG, adult height-PAH) were calculated. ResultsFollowing rhGH administration for 11.1±4.8months, GV-SDS increased from −2.5±1.7 to 3.5±4.3 (P=2×10−4), HI=8.5±3.7cm, HG=6.8±4.8cm and adult height was −1.8±0.9 SDS, compared to a PAH of −2.9±0.6 SDS (P=4×10−4). Knee score (P=2×10−3), GV at rhGH onset (P=8×10−3) and rhGH dose (P=8×10−3) were identified as predictors of HI and HG, but BA was not. ConclusionsOur study suggests that 1) a short period of rhGH administration can increase true adult height significantly in boys with ISS at time of near-ending growth; and 2) knee score rather than BA should be used to identify rhGH responders. These preliminary observations await confirmation by larger randomized trials.