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

Abstract

Context: Growth hormone (GH) deficiency in a child with short stature is diagnosed by GH secretion provocative tests. When the test response is considered adequate, the short stature is considered idiopathic (ISS).

Objective: To determine the effect of GH provocative tests on the growth rate in children with idiopathic short stature.

Design: Children with short stature with a normal response to at least one GH provocative test were enrolled. Height and growth velocity were measured prior to 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 Scores (SDS) using reference ranges standardized by age and sex. GH provocative tests employed arginine or clonidine as secretagogues.

Results: Fourty-six children of both genders were enrolled. In thirty-six children, height was measured at the time of testing and on an average time prior to and after the tests of 210 days and 180 days respectively. After testing the children displayed a 3.4-fold increase in their estimated 90-day growth rate. The median (inter-quartile range, IQR) 90 days growth of children pre-and post-tests were 0.7 (0.2-1.0) cm and 2.4 (1.7-3.1) cm respectively with a mean 3,4-fold increase (p < 0.0001). The median (IQR) 90 days growth of children pre- and post-tests calculated as standard deviation scores (SDS) were -4.0 (-5.4--2.1) SDS and 0.1 (-1.9-1.4) SDS respectively (p < 0.0001). Ten children with ISS were observed for about 5 months before the GH provocative tests. A small increase in the growth rate was seen only in 2 out of 10 children before testing while it increased in all of them after the tests. The difference in the median growth rate at the first and the 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 yet to be determined.

Keywords: GH provocative tests; Growth hormone deficiency; Short stature.