Weight-loss surgery restores testosterone levels in obese men

A common weight-loss surgery in obese men may not only help them shed flab but also improve their testosterone levels, leading to other health benefits, according to a new study.
Surgeons from Stanford University in California found that after undergoing the bariatric surgical procedure called sleeve gastrectomy, obese patients with low testosterone levels experienced a measurable increase in their testosterone levels over a 12 month-period following the operation.
"When men are obese, they have low testosterone. Men with low testosterone have more cardiac events than men with normal testosterone," said co-author John Morton, from the Stanford University School of Medicine.

"Low testosterone also increases the risk of sarcopenia, a loss of muscle that accelerates the ageing process, so it has an impact on many different levels," he said.
The researchers studied the effect of surgical weight loss on serum testosterone, DHEA (a precursor to testosterone), and prostate-specific antigen (PSA).
The clinical study involved 24 obese male patients undergoing sleeve gastrectomy at Stanford Hospital.

Serum testosterone, DHEA, and PSA were measured before and at three, six, and 12 months after the procedure.
The researchers found that the study group experienced a significant increase in average serum testosterone after undergoing sleeve gastrectomy.

At 12 months, testosterone had increased on average from 295 to 423 nanogrammes per decilitre. The normal range for circulating testosterone is 300 to 1000 nanogrammes per decilitre. A person is diagnosed with low serum testosterone when the level drops below 300 nanogrammes per decilitre.
Before the procedure, 63 per cent of participants had low testosterone and afterwards, only 41 per cent did. The average BMI was 46 before surgery and 31 after the operation.
In addition, DHEA also rose, from 12.8 to 39.6 nanogrammes per millilitre, and serum PSA concentration rose over 12 months from 0.62 to 0.75 nanogrammes per millilitre with no change in PSA mass, which is a marker for prostate cancer progression.

During the sleeve gastrectomy operation, the surgeon removes about 75 per cent of the stomach, leaving a narrow tube or "sleeve" the size of a banana.
The result is that patients feel full after eating small amounts of food. People with a body mass index (BMI) greater than 35 with a medical problem, or a BMI greater than 40, are candidates for this operation.
"When you are obese, your fat becomes converted to estrogen, which will compete with testosterone and drive it down," Morton said.
"The nice thing about what this process does is it creates an autotransfusion of testosterone from yourself," Morton said.

"This process occurs because you are losing weight, and therefore losing that estrogen, causing your natural testosterone stores to rise," he said.