GH and IGF-I deficiency are associated with reduced loss of fat mass after laparoscopic-adjustable silicone gastric banding

GH secretion is reduced in obese subjects and increases after body weight loss. It is still unclear if changes in the GH/IGF-I axis after laparoscopic-adjustable silicone gastric banding (LASGB) are associated with changes of body composition. OBJECTIVE: To analyse the relationships between changes in the GH/IGF-I axis and those of body weight and composition before and after LASGB. DESIGN: Observational, prospective. SETTING: University 'Federico II' of Naples (Italy). PATIENTS: Seventy-two severely obese females (BMI: 44.9 +/- 4.68; mean age: 33.1 +/- 11.34 years) were studied. MAIN OUTCOME MEASURES: GH peak after GHRH plus arginine test, IGF-I, IGFBP-3 and ALS levels, fat mass (FM) and free fat mass (FFM) (by Bioelectrical Impedance Analysis) at baseline and 6 months after LASGB. The change in percentage of individual variables was calculated as well as that of excess of body weight loss (EBWL%). The FM%, FFM% and EBWL% were correlated with peak GH and IGF-I levels changes. RESULTS: At baseline, GH deficiency (GHD) (GH peak = 4.1 microg/l) was found in 22 patients (31%), 16 of them also had IGF-I deficiency (< -2SDS). IGF-I levels were inversely correlated with waist circumference (r = -0.72, P < 0.001) and FM% (r = -0.75, P < 0.001). Post-LASGB the patients were classified as follows: group (1) GH and IGF-I sufficient (n = 44; 61.1%); group (2) GH and IGF-I deficient (n = 14; 19.4%) and group (3) GH sufficient and IGF-I deficient (n = 14; 19.4%). The percentage changes of EWBL (P < 0.05, P = 0.051, respectively) and FM (P < 0.001, P < 0.01, respectively) were lower in groups (2) and (3) than in group (1). At the stepwise linear regression analysis, postoperative IGF-I levels were the strongest determinant of percent changes of FM (P < 0.0001), of FFM (P = 0.009) and of EBWL (P < 0.0001). CONCLUSIONS: IGF-I levels is the most sensitive to unfavourable changes in body composition 6 months after LASGB making investigation of the somatotropic axis useful in the evaluation of bariatric surgery outcomes.