Association of testosterone and sex hormone-binding globulin with fat distribution in men: a quantitative water-fat MRI study.

BACKGROUND

The dynamic interplay between body fat distribution and sex hormone metabolism has been drawing escalating interest, especially in light of the frequently observed fluctuations in these indicators among male obese patients. Furthermore, exploring this connection holds paramount importance for the effective treatment and prevention of male obesity-related diseases. This study examines the relationships between regional fat depots (visceral, subcutaneous, epicardial volumes) and tissue-specific fat content (liver, pancreas, vertebra, muscle) with circulating testosterone and sex hormone‑binding globulin (SHBG) levels in men.

METHODS

We recruited 26 male obese patients with a body mass index (BMI) of ≥28 kg/m2 as the obese group and 10 males with a normal BMI as the control group. Age, height, BMI, total testosterone (TT), free testosterone (FT), bioavailable testosterone (BT), and SHBG levels were measured and recorded for both groups. The volumes of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and epicardial adipose tissue (EAT), as well as the proton density fat fraction (PDFF) in the liver, pancreas, third lumbar vertebra (L3), and erector spinae muscles at the L3/4 level, were quantified using magnetic resonance imaging (MRI). Group comparisons were performed using an independent samples t-test or a Mann-Whitney U test, as appropriate. Associations between fat metrics and hormone levels were assessed using Pearson/Spearman correlation and multiple linear regression adjusted for age and height.

RESULTS

Compared to the control group, the obese group exhibited significantly higher VAT volume (P=0.001), SAT volume (P<0.001), and EAT volume (P<0.001), liver PDFF (P=0.001), pancreas PDFF (P=0.031), and muscle PDFF (P=0.001), whereas L3 PDFF did not differ between groups (P=0.739). Serum TT, FT, BT (all P<0.01), and SHBG (P=0.003) were significantly lower in the obese group. After adjusting for age and height, multiple linear regression analysis revealed negative correlations of TT, FT, and BT, with the VAT volume (β=-0.348 to -0.384, all P<0.05) and EAT volume (β=-0.337 to -0.488, all P<0.05). SHBG was independently negatively associated with VAT volume (β=-0.301, P=0.041) and liver PDFF (β=-0.477, P=0.002).

CONCLUSIONS

Male testosterone levels are closely associated with VAT volume and EAT volume, while lower SHBG levels are strongly correlated with increased VAT volume and liver PDFF.