Growth hormone treatment response: associated factors and stimulated growth hormone secretion indices in prepubertal children with idiopathic GH deficiency

Abstract Purpose The aim of this study is to correlate the growth response in prepubertal children with idiopathic growth hormone (GH) deficiency after one year of treatment with growth hormone to the initial clinical and biochemical parameters. It also aims to study the secretory dynamics of GH by analyzing the profiles of GH stimulation tests in relation to the recombinant GH (rhGH) treatment response.Methods This a retrospective study which included 84 prepubertal children (47 males and 37 females) with a definitive diagnosis of GH deficiency. The GH secretory indexes GHmax, GH secretion rate (GHSR) and GH secretion volume (GHSV) were analyzed in relation to the response to rhGH treatment as defined by the index of responsiveness (IoR). Correlation and regression models were used to identify the best clinical and biochemical predictors to rhGH treatment.Results IoR was correlated negatively with the age (r=-0.607, p < 0.01) and positively with the distance of child’s height from its MPH r = 0.466 (p < 0.01) and pretreatment growth velocity (r = 0.247, p < 0.05). GH secretory indexes correlated together, with the highest association being observed between GHmax and GHSV (r = 0.883, p < 0.01). Regarding the GH secretory indexes, GHmax was the best predictor of IoR (β coef. = -0.514, p < 0.001) followed by the GHSV (β coef. = -0.47, p < 0.001) and GHSR (β coef. = -0.367 p < 0.001).Conclusions The age and the distance of child’s height from its MPH are major predictors of rhGH treatment response in children with idiopathic GH deficiency. The calculation of the other GH secretory indexes GHSR and GHSV are not better predictors of response to rhGH than GHmax. The combination of clinical and biochemical indexes may improve the pretreatment assessment of response to rhGH treatment.