The IGF-I Response to Growth Hormone Is Related to Body Mass Index in Short Children with Normal Weight

AIM: We investigated whether the insulin-like growth factor (IGF)-I response to growth hormone (GH) is regulated by body mass index (BMI) in short children with normal weight. METHODS: We studied 37 prepubertal children with idiopathic short stature (ISS), comparing children with high-normal BMI (standard deviation scores, SDS 1.23 +/- 0.11, n = 20) and low-normal BMI (SDS -0.93 +/- 0.12, n = 17). The IGF-I response to GH was determined with an abbreviated IGF-I generation test, by measuring serum IGF-I concentrations at baseline and 24 h after the administration of GH (0.033 mg/kg). RESULTS: Children with high- and low-normal BMI had similar age (8.5 +/- 0.7 vs. 8.7 +/- 0.7 years) and height (-2.0 +/- 0.1 vs. -2.2 +/- 0.2 SDS). However, children with high-normal BMI exhibited higher mean basal IGF-I (191 +/- 15 vs. 139 +/- 11 ng/ml, p < 0.05), higher mean IGF-I levels 24 h after GH administration (261 +/- 22 vs. 164 +/- 14 ng/ml, p < 0.05) and a higher IGF-I percent increase after GH administration (37 +/- 5 vs. 17 +/- 4%, p < 0.05) compared with children with normal-low BMI. CONCLUSION: BMI modulates the IGF-I response to GH, suggesting that GH sensitivity may be influenced by the nutritional status in children with ISS and normal body weight.