Effect of Roux-en-Y gastric bypass on testosterone and prostate-specific antigen.
BACKGROUND
Obese men have lower serum levels of testosterone, dehydroepiandrosterone (DHEA) and prostate-specific antigen (PSA), but an increased risk of dying from prostate cancer. The aim of this study was to examine the effect of surgically induced weight loss on serum testosterone, DHEA and PSA levels in obese men.


METHODS
Consecutive men undergoing Roux-en-Y gastric bypass (RYGB) participated in a prospective, longitudinal study. Main outcomes were changes were body mass index (BMI), percentage excess weight loss, serum levels of testosterone, DHEA and PSA, PSA mass and plasma volume, measured before operation and 3, 6 and 12 months later.


RESULTS
In 64 patients, mean BMI fell from 48.2 kg/m(2) before operation to 39.2, 35.6 and 32.4 kg/m(2) at 3, 6 and 12 months after RYGB. Testosterone levels rose significantly from 259 ng/dl to 386, 452 and 520 ng/dl respectively. Serum PSA levels increased significantly from 0.51 ng/ml to 0.67 ng/ml at 12 months. There were no significant changes in DHEA or PSA mass.


CONCLUSIONS
RYGB normalizes the serum testosterone level. PSA levels increase with weight loss and may be inversely correlated with changes in plasma volume, indicating that PSA levels may be artificially low in obese men owing to haemodilution.
Department of Surgery, Section of Minimally Invasive and Bariatric Surgery, Stanford University Medical Centre, Stanford, California 94305, USA.
G
G
Woodard
S
S
Ahmed
V
V
Podelski
T
T
Hernandez-Boussard
J
J
Presti
J M
JM
Morton
D015992:Body Mass Index; D003687:Dehydroepiandrosterone / Q000097:blood*; D057210:Delayed Diagnosis; D015390:Gastric Bypass; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood / Q000503:physiopathology / Q000601:surgery*; D010953:Plasma Volume / Q000502:physiology*; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D012307:Risk Factors; D013739:Testosterone / Q000097:blood*; D015431:Weight Loss / Q000502:physiology
D013739:Testosterone; D003687:Dehydroepiandrosterone; D017430:Prostate-Specific Antigen