Information on the associations of testosterone levels with abdominal muscle volume and density in men is limited, while the role of estradiol and SHBG on these muscle characteristics are unclear. Therefore, this study aimed to investigate the association between fasting serum sex hormones and CT-derived abdominal muscle area and radiodensity in adult men. Conducted as a cross sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis, our analyses focused on a community-based sample of 907 men aged 45-84 years, with 878 men having complete data. CT scans of the abdomen were interrogated for muscle characteristics, and multivariable linear regressions were used to test the associations. After adjustment for relevant factors, higher levels of both total testosterone and estradiol were associated with higher abdominal muscle area (1.74, 0.1-3.4, and 1.84, 0.4-3.3, respectively). In the final analyses, levels of total testosterone showed a positive association, while an inverse relationship was observed for SHBG with abdominal muscle radiodensity (0.3, 0.0-0.6, and - 0.33, - 0.6 to - 0.1, respectively). Our results indicate a complex association between sex hormones and abdominal muscle characteristics in men. Specifically, total testosterone and estradiol were associated with abdominal muscle area, while only total testosterone was associated with muscle radiodensity and SHBG was inversely associated with muscle radiodensity.Clinical Trial: NCT00005487.

Context

Earlier studies have investigated the role of obesity-related inflammation and endogenous sex hormones in men. The role of interleukin-6 (IL-6) and C-reactive protein (CRP) with testosterone and sex hormone binding globulin (SHBG) levels in men is still debated.

Objective

To investigate the independent association between levels of high sensitivity CRP (hsCRP) and IL-6 with endogenous sex hormones in men.

Design

Cross-sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis.

Patients or other participants

A community-based sample of 3212 men aged 45-84 years was included. After exclusions, 3041 men remained for the analyses.

Main outcome measure(s)

Serum concentrations of testosterone, SHBG, hsCRP, IL-6, and sTNFR were measured from the baseline exam. Multivariable linear regressions were used to examine the association of inflammatory markers with sex hormones.

Results

An inverse association was found between levels of hsCRP and levels of testosterone and SHBG, even after adjustment for confounders and IL-6 (Total Testosterone; B = -0.14, Bioavailable Testosterone; B = -0.06, and SHBG; B = -0.66). Similar results were found for IL-6, although a positive association was found for SHBG (B = 0.95). Notably, an inverse association was found for IL-6 with bioavailable testosterone in African Americans and Hispanic Americans aged 45-54 years. No associations were found for sTNFR and endogenous sex hormones.

Conclusion

Our results indicate that inflammatory markers have independent associations with levels of testosterone (total and bioavailable) and furthermore, appear to associate differently with SHBG levels.