Influence of Body Mass Index on Growth Hormone Responses to Classic Provocative Tests in Children with Short Stature

Abstract

Background: The diagnosis of growth hormone (GH) deficiency is based on a reduced peak GH response to provocative tests. However, the provocative tests are poorly reproducible and GH secretion is regulated by physiological parameters, such as body weight and puberty. The aim of this study was to assess the influence of body mass index (BMI) on GH response to provocative testing and to analyze the reproducibility of GH stimulation test. Methods: Clinical data were collected retrospectively by chart review from the Pediatric Endocrine Unit at the Ajou University Hospital. A total of 187 subjects with short stature who completed a GH stimulation testing between 2003 and 2009 were included in the study. Results: Of the 187 subjects, 66 (35.3%) had GH deficiency, while 121 (64.7%) were categorized as having idiopathic short stature. Reliability was calculated for 48 patients with idiopathic short stature who underwent the GH stimulation test twice. A GH response ≧10 ng/ml after retesting was found in 39 patients (81.3%) and a GH response <10 ng/ml was found in 9 patients (18.7%). In a stepwise multivariate analysis, BMI was a significantly independent predictor of peak GH. Elevated BMI was negatively associated with peak plasma GH levels. Conclusions: The lack of reliability of GH values in response to pharmacological stimuli should be taken into account in the diagnosis of GH deficiency. Also, higher BMI is associated with lower GH secretion. BMI should be measured and GH results appropriately interpreted for all subjects undergoing GH stimulation testing.

Revaluation of the clinical and metabolic behavior of children with isolated growth hormone deficiency during GH treatment according to newly proposed note 39 of the Italian Medicines Agency (AIFA)

“…Many different stimuli are currently used to induce GH secretion, but to date no stimulation test is completely reliable. The provocative tests are poorly reproducible, the GH cut-off is quite arbitrary and the GH peak response could be influenced by many factors, such as age, BMI, adiposity or pubertal status [10][11][12][13]. Some years ago Kristrom et al demonstrated that the growth response in ISS was similar to GHD children, despite the first required higher dose of GH [14], while other authors have demonstrated that there is no benefit in treating these groups of children [15,16].…”

Influence of Body Mass Index on the Growth Hormone Response to Provocative Testing in Short Children without Growth Hormone Deficiency

“…Spontaneous GH secretion is suppressed in children with a high body mass index (BMI) (5). Recent studies of short children, including those with GHD, have reported that higher BMI was related to a lower peak stimulated GH level (9-11). However, it is not clear whether there is a similar association between BMI and peak GH level in short normal children without GHD.…”

Hormone replacement therapy in children: The use of growth hormone and IGF-I

“…Thereby obese children show diminished GH responses [14,15]. In adults this phenomenon has been previously described [16,17] and has found its consideration in the cut-off levels of adult GHtesting [18].…”