Surgery Reverses Obesity-Related Hypogonadism

Blood tests were performed before and one month after surgery to measure total plasma testosterone, the sex hormones dihydrotestosterone (DHT), estradiol, luteinising hormone (LH), follicle-stimulating hormone (FSH), sex hormone binding globulin (SHBG), prostatic-specific antigen (PSA), and leptin. A group of 19 healthy age-matched, non-obese, male subjects served as a control.

Among the obese subjects, 51.6% suffered from hypogonadism, and of those who had subnormal total testosterone, those with metabolic syndrome (45.2%) showed lower plasma testosterone than men without metabolic syndrome. BMI and waist circumference were found to be negatively correlated with total testosterone and plasma LH levels. The obese males had lower plasma testosterone (10.8 nmol/L) than healthy subjects (15.7 nmol/L), higher estradiol levels, and lower LH and FSH levels. No differences were observed between the two groups in their DHT and PSA levels.

The results revealed that one month after the sleeve gastrectomy procedure, obese subjects showed a significant weight reduction (averaging 17.2 kg) and the proportion with hypogonadism had fallen to just 11.6%. At the same time, average testosterone levels increased by 85%, to a level greater than that observed in the healthy control group (18.9 nmol/L), and estradiol levels fell by 35%. Surprisingly, PSA levels rose by 70%. The study was presented at the European Congress on Obesity (ECO), held during May 2018 in Vienna (Austria).

“Obesity in men is associated with hypogonadism, a condition in which production of testosterone is reduced, while estrogen levels are elevated,” said senior author Professor Marco Rossato, MD, and colleagues. “These effects seem to be the result of excess body fat interfering with sex steroid metabolism which leads to increased aromatization of androgens (such as testosterone) into estrogens within the adipose tissue itself. It follows that weight loss should improve this hormonal imbalance, and contribute to a reversal of hypogonadism.”

Hypogonadism in men refers to a diminished functional activity of the gonads, resulting in diminished testosterone biosynthesis. Other hormones produced by the gonads that hypogonadism can decrease include progesterone, DHEA, anti-Müllerian hormone, activin, and inhibin. In men, it can cause reduced body hair and beard, enlarged breasts, loss of muscle, and sexual difficulties.

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