Effects of gastric bypass on the GH/IGF-I axis in severe obesity – and a comparison with GH deficiency

• Published in: European journal of endocrinology Vol. 154; no. 1; pp. 53 - 59
• Main Authors: Engström, Britt Edén, Burman, Pia, Holdstock, Camilla, Öhrvall, Margareta, Sundbom, Magnus, Karlsson, F Anders
• Format: Journal Article
• Language: English
• Published: Colchester European Society of Endocrinology 01.01.2006; Portland Press
• Subjects: Adult; Biological and medical sciences; Body Mass Index; Clinical Studies; Comparative Study; Endocrinopathies; Female; Fundamental and applied biological sciences. Psychology; Gastric Bypass; Glucose - metabolism; Homeostasis; Human Growth Hormone - deficiency; Human Growth Hormone - secretion; Human Growth Hormone/deficiency/secretion; Humans; Insulin-Like Growth Factor I - secretion; Male; Medical sciences; Middle Aged; Obesity - physiopathology; Obesity - surgery; Obesity/physiopathology/surgery; Vertebrates: endocrinology; Endocrinopathy; Stomach; Obesity; Digestive system; Deficiency; Nutrition disorder; Somatotropin hormone; Treatment; Adenohypophyseal hormone; GH-IGF axis; Bypass; Surgery; Endocrinology; Nutritional status; Comparative study
• ISSN: 0804-4643; 1479-683X
• DOI: 10.1530/eje.1.02069

Objective: Overfeeding suppresses GH secretion and makes evaluation of a suspected GH deficiency (GHD) difficult. In normal weight subjects, gender is known to influence GH concentrations, which is most apparent in the ambulatory, morning-fasted state. In this study, we examined the GH/IGF-I axis in obese men and women and the effect of surgically induced weight loss. Design: Sixty-three subjects (body mass index (BMI) 45 ± 6 kg/m2; 54 women, 9 men) were studied prior to, and 6 and 12 months following Roux-en-Y gastric bypass (RYGBP) surgery. Fifty-four patients with classic GHD (BMI 27 ± 6 kg/m2; 35 men, 19 women) were included for comparison. Methods: Hormones were analysed in fasting morning serum samples. Results: RYGBP resulted in a decreased BMI to 35 ± kg/m2 at 6 months and 32 ± 6 kg/m2 at 12 months. GH and IGF-I increased at 6 months in the women and at 12 months in both sexes by ≥ 300 and 11% respectively. Prior to RYGBP, GH concentrations were low in the obese men and similar to those of GHD men (mean 0.09 mU/l). Obese women had tenfold higher values than obese men and sevenfold higher than GHD women. IGF-I levels were in the low reference range in the obese and below −2 s.d. for age in 13%. Conclusions: Surgically induced weight loss partially restores GH secretion. Despite a marked suppression of GH values, a gender influence is maintained in severe obesity. In obese women, single morning GH and IGF-I values seem sufficient to exclude a suspicion of classic GHD.