Effect of body mass index on peak growth hormone level after growth hormone stimulation test in children with short stature.

Purpose: The aim of this study is to evaluate the effect of body mass index (BMI) on peak serum growth hormone (GH) level after GH stimulation test in children with short stature.

Methods: Data was obtained from retrospective medical records review of those who visited the pediatric endocrine clinic at St. Vincent's hospital of Catholic university for short stature from January 2010 to June 2019. A total 115 children (66 boys and 49 girls) whose height was less than 3 percentiles according to age and sex underwent GH stimulation test.

Results: Of 115 subjects, 47 were diagnosed with GH deficiency (GHD) and 68 were diagnosed with idiopathic short stature (ISS). In patients with GHD, weight standard deviation score (SDS) (P < 0.001) and BMI SDS (P ≤ 0.001) were higher and free thyroxine (T4) level (P = 0.012) was lower than those in the ISS group. In total subjects, peak serum GH level after GH stimulation test showed negative correlations with weight SDS (r = -0.465, P < 0.001), BMI SDS (r = -0.398, P < 0.001), thyroid stimulating hormone (r = -0.248, P = 0.008) and a positive correlation with free T4 (r = 0.326, P < 0.001). In multiple regression analysis, BMI SDS (P = 0.003) was negatively associated with peak serum GH level in GH stimulation test after adjusting for age, sex, pubertal status and type of pharmacological stimulus.

Conclusion: BMI SDS influence peak serum GH level after GH stimulation test. We should consider BMI factor when interpreting of results of GH stimulation test.