Serum testosterone levels and their association with selected anthropometric parameters obtained by dual-energy X-ray absorptiometry: a population-based study.

Introduction: Testosterone plays an important role in men's health.

Objectives: The aim of the study was to assess serum concentrations of total testosterone (tT) and free testosterone (fT) in men and to investigate the association of their levels with anthropometric parameters.

Patients and methods: A cross‑sectional population‑based survey was conducted among 701 men aged 20-64 years included in the Bialystok PLUS study (Poland). Dual‑energy X‑ray absorptiometry was used to assess body composition.

Results: Median (interquartile range [IQR]) serum tT concentration was 4.39 (3.4-5.7) ng/ml, and median (IQR) serum fT concentration was 339.41 (277.4-403.7) pmol/l. In the overall study population and among men aged 20-34 years, tT concentrations were negatively associated with body fat mass and android fat distribution. Among men aged 35-49 years, tT levels were negatively associated with body fat mass and android fat distribution, but positively associated with lean body mass. In the 50-64 years age group, tT concentrations were negatively related to body fat mass and positively related to lean body mass. Across the entire cohort and within each age subgroup, lower fT concentrations were linked to higher body fat mass. A positive relationship between lean body mass and fT levels was noted in the 35-49 years age group.

Conclusions: In the overall population and across all age groups, higher fat mass was linked to lower serum tT and fT concentrations. In younger men, an android pattern of fat distribution was associated with lower tT levels, whereas greater lean body mass in older men was tied to higher tT and fT concentrations. Testosterone levels are significantly related not only to body weight, but also to body composition.