MON-248 Impact of Body Mass Index on Peak Growth Hormone Response to Provocative Testing and Therapeutic Outcome in Children with Growth Hormone Deficiency

Abstract

Introduction: The growth hormone (GH) stimulation test can be influenced by various factors, including type of GH stimuli, age, body mass index (BMI), and pubertal state. It is known that GH secretion is inversely related to BMI, but there is no available BMI - specific cut off value in children with growth hormone deficiency (GHD). The purpose of the study was to evaluate the therapeutic response according to obesity and relationship between GH secretion and BMI in children with GHD Methods: Among the GHD patients met the inclusion criteria, 460 patients conducted insulin stimulation test in common were enrolled for this study. Of these, the group were divided into idiopathic GHD (n=439), organic GHD (n=21), complete GHD (n=114), and partial GHD (n=325). We compared the variables including age, peak GH level, bone age, height standard deviation score (SDS), BMI SDS, and insulin-like growth factor-1 (IGF-1) SDS of each group. Results: Of the 439 patients with idiopathic GHD, 385 patients were normal (88%), 28 patients were overweight (6%), and 26 patients were obese (6%). The peak GH for the insulin stimulation test was 4.7 in obese group and 5.1 in non-obese group. The peak GH in organic GHD was 1.6 for obesity and 3.1 for non-obese group. According to the multiple regression analysis, the peak GH was significantly reduced by 1.06 as BMI SDS was increased by 1 in patients with complete GHD (p=0.03). The cutoff value of complete GHD in obese children was lower than that of non-obese group [response to insulin: obese group ≤ 4.7 (area under the curve AUC= 0.87, 95% CI 0.7-1.0), non-obese group ≤ 4.92 (AUC= 0.83, 95% CI 0.80-0.87); response to L-dopa: obese group ≤ 4.3 (AUC= 0.90, 95% CI 0.76-1.0), non-obese group ≤ 4.9 (AUC= 0.83, 95% CI 0.79-0.87)]. IGF-1 SDS and height SD at initiation of GH therapy of obese group were higher than those of non-obese group, but the height gain during GH therapy between two groups was similar. Regardless of obesity, therapeutic response of the first year of GH therapy was better than the second year of treatment. Conclusion: The BMI and GH peak of obese children with GHD shows inverse correlation, with a relatively low cutoff value. Further comparative research to better understand of the relationship between BMI and GH secretion with simple obese children is needed to expand clinical application.