Lower testosterone, increased LH levels indicate impaired testicular function in older men

Several factors contribute to the variation in male testosterone, sex hormone-binding globulin (SHBG), and luteinizing hormone (LH) concentrations, suggests a study. Moreover, reduced testosterone and elevated LH levels appear to be signs of an impaired testicular function after age 70 years.

A systematic literature search of prospective cohort studies of community-dwelling men with total testosterone measured using mass spectrometry was conducted up to July 2019 to determine the factors associated with differences in sex hormone concentrations.

Individual participant data (IPD) were obtained from nine studies (n=21,074) and aggregate data from two studies (n=4,075). The authors extracted sociodemographic, lifestyle, and health factors and concentrations of total testosterone, SHBG, LH, dihydrotestosterone, and oestradiol.

In the two-stage random-effects IPD meta-analyses, nonlinear associations of testosterone with age, with negligible change among men aged 17‒70 years (change per SD increase about the midpoint, ‒0.27 nmol/L, 95 percent confidence interval [CI], ‒0.71 to 0.18) and decreasing testosterone levels with age for men aged >70 years (‒1.55 nmol/L, 95 percent CI< ‒2.05 to ‒1.06) were observed.

Testosterone also showed an inverse association with body mass index (BMI; change per SD increase, ‒2.42, nmol/L, 95 percent CI, ‒2.70 to ‒2.13).

In addition, testosterone concentrations were lower for married men (mean difference [MD], ‒0.57 nmol/L, 95 percent CI, ‒0.89 to ‒0.26), those who undertook at most 75 min of vigorous physical activity per week (MD, ‒0.51 nmol/L, 95 percent CI, ‒0.90 to ‒0.13), former smokers (MD, ‒0.34 nmol/L, 95 percent CI, ‒0.55 to ‒0.12), or those who had hypertension (MD, ‒0.53 nmol/L, 95 percent CI, ‒0.82 to ‒0.24), cardiovascular disease (MD, ‒0.35 nmol/L, 95 percent CI, ‒.55 to ‒0.15), cancer (MD, ‒1.39 nmol/L, 95 percent CI, ‒1.79 to ‒0.99), or diabetes (MD, ‒1.43, 95 percent CI, ‒1.65 to ‒1.22).

Notably, SHBG correlated directly with age and inversely with BMI. LH was also directly associated with age in men aged >70 years.

“Interpretation of individual testosterone measurements should account particularly for age older than 70 years, obesity, diabetes, and cancer,” the authors said.