Is it Time to Test the Effect of Weight Loss on Testosterone?

Abstract

Testosterone is a sex-steroid hormone, synthesized in the testes, with biologic effects on numerous tissues. Low circulating concentrations, seen with testicular or hypothalamic–pituitary defects, are often associated with decreased sexual function, muscle mass, and poor quality of life, along with a risk of osteoporosis. Primary testicular failure can be due to testicular trauma, chemotherapy, radiation therapy, or chromosomal abnormalities, although secondary causes, also termed centrally mediated hypogonadism, are associated with pituitary tumors or hypothalamic disease. In addition to these well-known etiologies, there is an increasing appreciation that hypogonadism can be the result of aging, medications, and chronic diseases. A physiological decrease in testosterone concentrations has been well documented after the fourth or fifth decade of life and has been postulated to result from a decline in both testicular and hypothalamic–pituitary function. In scenarios in which the patient has a clear pathophysiologic mechanism for the hypogonadism, treatment with testosterone is nearly always recommended to alleviate symptoms of hypogonadism and maintain secondary sexual characteristics (1). Men on replacement therapy should be monitored for polycythemia, falls in serum high-density lipoprotein, worsening of sleep apnea, and increase in prostate-specific antigen concentrations (2, 3). Because long-term evidence of safety with supplementation is yet to be established, testosterone therapy is not routinely recommended in older men or in men with an unclear underlying etiology for their low testosterone concentrations. Because low serum testosterone is commonly observed in chronic illness, there may be less invasive ways to naturally increase serum concentrations. This circumstance creates an opportunity to explore other intervention options that could favorably increase the endogenous testosterone production in the absence of potential side effects. The interpretation of laboratory tests can be confusing in men as they age and become more obese because both factors modulate sex by hormone-binding globulin (SHBG)3 concentrations. Obese …