GH provocative tests stimulate the growth in children with idiopathic short stature

Abstract

Abstract Context: Growth hormone (GH) deficiency in a child with short stature is diagnosed by GH secretion provocative tests. When tests response is considered adequate, the short stature is considered idiopathic (ISS), and no GH replacement therapy is advised. Objective: To determine the effect of GH provocative tests on growth rate in children with idiopathic short stature. Design: Children with short stature with normal response to two GH provocative tests, were enrolled. Height and growth velocity were measured prior and after stimulus tests during the follow-up. Methods Height, mid-parental height, body weight, and body mass index were measured. The height and growth rate were converted to percentiles and Standard Deviation Score (SDS) using reference ranges standardized for age and sex. GH provocative tests employed arginine or clonidine as secretagogues. Results: Thirty-one children of both genders were enrolled. Heights were measured at test time and at a mean time prior and after the tests of 205 days and 192 days respectively. After the tests the children displayed a 3.8-fold increase in their estimated 90 days growth rate. The mean growth rate of children pre- and post-tests were -4.0 SDS and 0.3 SDS respectively (p<0.0001). Ten children with ISS were observed for about 5 months before the GH provocative tests. A small increase in growth rate was seen in only 2 of 10 children with ISS before the tests while it increased in all after the tests. The difference of the mean growth rate at first and second observation was not significant (p= 0.219). Conclusions: Two sequential somatotropic axis provocative tests increase the growth rate in children with idiopathic short stature. The duration of this effect is to be determined.