Low T Doesn't Reduce Effectiveness of Bariatric Surgery in Men

Though women comprise as much as 80% of patients who undergo bariatric surgery, more information on the effects of the procedure in men is needed.

A particular concern is the tendency for obese men to have markedly reduced serum testosterone (T) levels and obesity-related hypogonadotropic hypogonadism (OrHH). This disorder is characterized by reduced serum T with relatively high estradiol (E₂), as well as inappropriately low luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels. As OrHH seems to reverse after substantial weight lost, more studies of bariatric surgery in men are needed.

Researchers from Radboud University’s Nijmegen Medical Centre in the Netherlands enrolled 13 men diagnosed with OrHH (free T< 225 pmol/L) and 11 age-matched eugonadal morbidly obese men (free T> 225 pmol/L) in an observational study. The goal of the study was to evaluate bariatric surgery’s effects in obese men on free T levels. To do so, the researchers measured serum gonadal hormones, body composition, glucose, lipid, and bone metabolism during the first year after bariatric surgery.

The authors determined that serum-free T was inversely related to body weight and rose gradually after bariatric surgery in both eugonadal and OrHH men. The magnitude of the changes was 30 pmol/L for every 10 kg of weight loss. Three OrHH patients who experienced serum-free T remained within the hypogonadal range despite substantial weight loss.

At one year, patients in both arms of the study had similar outcomes. Thus, a diagnosis of OrHH did not reduce the efficacy of bariatric surgery.

Testosterone/estradiol balance disturbances vary significantly among obese men, which probably reflect differences in the degree of patients’ aromatase activity. Weight loss reduces excess aromatase activity and can normalize estradiol/testosterone balance in most obese men. A subset of obese men may have an additional condition that contributes to low T levels.