Rethinking Low Testosterone in Older Men: Association With Obesity Rather Than Aging.

Objective: The decline in testosterone levels among older men remains a subject of debate. While some cross-sectional and longitudinal studies have reported a decrease in testosterone with advancing age, others have not observed this trend. In this study, we aimed to evaluate testosterone levels and identify predictors of low testosterone in an age-stratified cohort of men.

Methods: From January 2016 to June 2022, a cohort of men receiving routine care at a primary care center was prospectively analyzed. Participants were stratified into age groups: 45-64 years (middle-aged), 65-74 years (young-old), 75-84 years (middle-old), and ≥85 years (oldest-old). Comprehensive clinical and laboratory assessments were conducted, including waist circumference, glucose levels, triglycerides, HDL cholesterol, and total testosterone. Low testosterone was defined as levels below 300ng/dL. Metabolic syndrome was diagnosed in accordance with established diagnostic criteria.

Results: The study included 3.489 subjects across age groups. Median testosterone levels were similar across all age groups. The prevalence of low testosterone was around 20% in all groups and did not significantly vary with age. Obesity, as indicated by increased waist circumference (WC) >102 cm, was strongly associated with low testosterone. The prevalence of low testosterone increased from 8% in those with WC≤93cm to 44% in those with WC≥110cm.

Conclusion: This study highlights the significant association between low testosterone levels and obesity, reinforcing the importance of addressing comorbidities in testosterone decline.