Kate Johnson of the Montreal Bureau contributed to this report.
MONTREAL — Men who are overweight or obese have reduced serum testosterone levels, “which may help explain idiopathic oligospermia,” according to William E. Roudebush, Ph.D.
In his study of 90 men, “there was a substantial and significant reduction in testosterone of roughly 25%, regardless [of whether] they were overweight or obese,” said Dr. Roudebush, who presented his findings at the joint annual meeting of the American Society for Reproductive Medicine and the Canadian Fertility and Andrology Society.
“Rather than infertility therapy, maybe something as simple as weight reduction could work,” he said in an interview. “Medical literature states that as BMI increases, there's an increased conversion of testosterone to estradiol. Excess estradiol can cause a negative impact on testicular function. We know that [men are] going to have dysfunctional spermatogenesis based on that.”
In his observational study of 90 men with a mean age of 34, Dr. Roudebush and his associates at the Atlanta-based Reproductive Biology Associates compared patient BMI scores with their serum levels of testosterone, FSH, LH, and prolactin, as measured by chemiluminescence. Men were grouped by weight according to published BMI values: normal was defined as 20–24 kg/m
The mean values were 28.50 for BMI; 459 ng/dL for testosterone; 5.21 mU/mL for FSH; 3.69 U/L for LH, and 8.96 ng/mL for prolactin.
The analysis revealed an inverse relationship between BMI and serum testosterone levels. The mean serum testosterone level in the normal BMI group was 565 ng/dL, compared with almost 429 ng/dL in the overweight group and almost 416 ng/dL in the obese group.
No other reproductive serum markers had a significant relationship with BMI, but LH level approached significance. “We ran testosterone tests on everybody, but we did not have the approval to run the LH tests across the board, so we did not get enough values back to show statistical significance,” he said.
Beckman Coulter Inc. provided the testosterone test kits. Dr. Roudebush disclosed that he is a paid consultant for Beckman Coulter.