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

Abstract

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. To analyse the relationships between changes in the GH/IGF-I axis and those of body weight and composition before and after LASGB. Observational, prospective. University 'Federico II' of Naples (Italy). Seventy-two severely obese females (BMI: 44.9 +/- 4.68; mean age: 33.1 +/- 11.34 years) were studied. 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. 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). 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.