Effects of growth hormone treatment in obese prepubertal boys

Childhood obesity is associated with several abnormalities of the GH axis, including decreased spontaneous secretion, decreased response to exogenous secretagogues, and altered pulsatile pattern of secretion. In adults, GH treatment reduces abdominal obesity and improves insulin sensitivity, as well as blood lipid profiles. Whether GH has similar effects in obese children has not been investigated previously. In this study, seven prepubertal severely obese boys aged 10-12 yr were treated with GH for 6 months and followed for an additional 6 months. No diet or exercise modifications were initiated. Body fat percentage decreased from 51.3% to 46.1% after treatment (P = 0.03). Frequently sampled iv glucose tolerance tests revealed an increased responsivity of the acute insulin secretion (P = 0.04) and a nonsignificant trend toward improved insulin sensitivity. In isolated adipocytes, the maximum isoprenaline- and terbutaline-induced lipolysis were increased approximately 2.5-fold (P = 0.02). The sensitivity of the adipocytes to isoprenaline was unchanged, whereas the sensitivity to terbutaline was increased (P = 0.04). No effect was observed on basal or insulin-stimulated lipogenesis. In conclusion, GH treatment for 6 months of obese prepubertal boys reduces body fat, possibly, via stimulation of catecholamine-induced lipolysis, without negative effects on glucose homeostasis.