Relationship between growth hormone/insulin-like growth factor-1 axis integrity and voluntary weight loss after gastric banding surgery for severe obesity.

BACKGROUND: The aim of this observational study was to determine, in a retrospective analysis, whether growth hormone (GH) and insulin-like growth factor-1 (IGF-1) at baseline or changes in the GH/IGF-1 axis after laparoscopic adjustable gastric banding (LAGB) is associated with weight loss and body composition changes in severely obese nondiabetic patients. METHODS: Weight loss (expressed as percent excess weight loss [EWL%]), anthropometry, body composition by bioelectrical impedance analysis (BIA), serum IGF-1, and GH peak after GH-releasing hormone (GHRH) plus arginine (ARG) test were measured and expressed as standard deviation scores (SDS) of reference values in 104 women and 36 men, age (mean +/- SD) 34 +/- 11 and 30.2 +/- 11 years, and BMI 44 +/- 5.7 and 39 +/- 3.2, respectively, before and 6 months after LAGB. RESULTS: After LAGB, 25% of women and 22.5% of men had GH deficiency, while 30.8% of women and 33.3% of men had IGF-1 deficiency or insufficiency. The median EWL was 36.8% in women and 40.0% in men. In both genders, percent decrease of waist circumference, EWL, and fat mass (FM) and percent increase of fat-free mass (FFM) was greater in patients with normal GH secretion and IGF-1 levels. The GH peak after GHRH + ARG, IGF-1 levels, and IGF-1 SDS were inversely correlated with EWL% (r = -0.50, r = -0.53, and r = -0.42, respectively; p < 0.0001) and percent FM (r = -0.41, r = -0.36, and r = -0.35, respectively; p < 0.0001). In stepwise linear regression analysis, the GH peak after GHRH + ARG was the major determinant of EWL% (p < 0.0001) and FM (p = 0.001). CONCLUSIONS: The efficacy of LAGB was greater in the patients with a normal GH response to GHRH + ARG and with normal IGF-1 levels. The percent of FM, FFM, and EWL were significantly correlated with the GH response to GHRH + ARG and with IGF-1 levels.