As men age, testosterone levels decrease, but current guidelines recommend testing in symptomatic men only, and there has been a lack of consensus about what point that decrease becomes a deficiency.
Healthy aging men have been presumed to have higher serum testosterone levels than their counterparts with obesity, smoking history, or associated comorbidities, but large-scale evidence to support the notion that has been lacking, according to a study published in July in the Journal of the Endocrine Society. Furthermore, with all of the recent controversy surrounding testosterone supplementation, evidence-based guidelines are needed for what circulating testosterone levels to target when interventions are warranted.
Researchers led by Elizabeth A. Platz, ScD, MPH, of the Johns Hopkins Bloomberg School of Public Health in Baltimore, Md., set out to document testosterone levels in never-smoking lean men in order to establish those guidelines for aging men, men with aging-associated comorbidities, and obese men using 10 years’ worth of National Health and Nutrition Examination Survey (NHANES) data in “Nationally Representative Estimates of Serum Testosterone Concentration in Never-Smoking, Lean Men Without Aging-Associated Comorbidities.”
From immunoassays done during two phases of NHANES, they determined that serum testosterone levels were indeed significantly higher in never-smoking lean men in three age cohorts (20 to 39, 40 to 59, and >60), ranging from 4% to 9% higher in the morning-only assays to 13% to 24% higher in the continuous assays.
“In this analysis of U.S. nationally representative data, we provided typical levels of serum testosterone in healthy middle-aged and older men—never-smoking, lean men without certain common conditions—to inform guidelines for doctors caring for aging men with testosterone deficiency and to inform trials aiming to raise testosterone in aging men by lifestyle changes” Platz says.
Thus, from their public health perspective, the team believes that nonpharmacologic interventions to increase serum testosterone might be better than testosterone supplementation for overall health and to avoid adverse effects. In other words, would losing weight, exercising, and avoiding smoking normalize testosterone levels in older men to the target levels they have identified? They see a need for large-scale trials designed to test whether increasing lean mass and decreasing adiposity would be effective testosterone therapy in some men. Such a nonpharmacologic intervention might be appropriate even for asymptomatic aging men.
This is the 33rd study from the Hormone Demonstration Program supported by the Maryland Cigarette Restitution Fund at Johns Hopkins. This work was also supported by a National
Cancer Institute (NCI) National Research Service Award and by an NCI Cancer Center Support Grant.