Effect of gastric bypass on spontaneous growth hormone and ghrelin release profiles.
OBJECTIVE
The purpose of this study was to analyze growth hormone (GH) concentrations in obese women before and after Roux-en-Y gastric bypass (RYGBP) and how resulting changes in weight, fat mass, ghrelin levels, and insulin sensitivity affect GH secretion.


METHODS
Blood was sampled at 20-minute intervals for 24 hours in 10 non-diabetic premenopausal severely obese women before and 6 months after RYGBP. GH concentrations were measured in all samples, and serum ghrelin was collected at five time-points.


RESULTS
After a 27% BMI drop (55.9 +/- 6.2 to 40.7 +/- 5.8 kg/m2), blunted GH profiles underwent partial recovery. Basal, postprandial, and mean ghrelin concentrations were not changed. A negative correlation was found between mean GH levels and insulin and homeostasis model assessment (p < 0.01). BMI accounted for 54% of GH variation.


CONCLUSIONS
Partial recovery of GH secretion after RYGBP-induced weight loss suggests that a blunted secretion is not a causal factor of obesity but a consequence of the obese state and does not seem to be ghrelin-level dependent.
Mancini
Marcio C
MC
Obesity and Metabolic Syndrome Unit, Endocrinology Service, Hospital das Clínicas, São Paulo University School of Medicine, São Paulo, Brazil. mmancini@usp.br
Costa
Ana P A C
AP
de Melo
Maria Edna
ME
Cercato
Cintia
C
Giannella-Neto
Daniel
D
Garrido
Arthur B
AB
Rosberg
Sten
S
Albertsson-Wikland
Kerstin
K
Villares
Sandra M F
SM
Halpern
Alfredo
A
D000328:Adult; D001823:Body Composition; D001835:Body Weight / Q000502:physiology; D005260:Female; D015390:Gastric Bypass; D054439:Ghrelin; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008137:Longitudinal Studies; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000503:physiopathology / Q000601:surgery*; D036361:Peptide Hormones / Q000097:blood / Q000378:metabolism*; D019518:Postprandial Period / Q000502:physiology; D011446:Prospective Studies
D054439:Ghrelin; D036361:Peptide Hormones; D013006:Growth Hormone