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


METHODS
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 > or = 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.
Edén Engström
Britt
B
Department of Medical Sciences, Internal Medicine, Uppsala University Hospital, Sweden. britt.eden_engstrom@medsci.uu.se
Burman
Pia
P
Holdstock
Camilla
C
Ohrvall
Margareta
M
Sundbom
Magnus
M
Karlsson
F Anders
FA
D000328:Adult; D015992:Body Mass Index; D005260:Female; D015390:Gastric Bypass; D005947:Glucose / Q000378:metabolism; D006706:Homeostasis; D019382:Human Growth Hormone / Q000172:deficiency* / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology* / Q000601:surgery*
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D005947:Glucose