Visceral and subcutaneous adipose tissue assessed by magnetic resonance imaging in relation to circulating androgens, sex hormone-binding globulin, and luteinizing hormone in young men.

CONTEXT

No large studies of young men have examined circulating sex hormones in relation to visceral and sc adipose tissues.

OBJECTIVE

The aim of this study was to investigate the role of visceral adipose tissue and sc adipose tissue on circulating sex hormones and the impact of obesity on sex hormone reference intervals.

DESIGN, SETTING, AND PARTICIPANTS: Population-based study of 783 Danish 20- to 29-yr-old men was performed using dual-energy x-ray absorptiometry in all men and magnetic resonance imaging in 406 men.

MAIN OUTCOME MEASURES

Total, bioavailable, and free testosterone, dihydrotestosterone (DHT), total and bioavailable estradiol, SHBG, and LH were measured.

RESULTS

In multiple regressions, visceral adipose tissue was an independent, inverse correlate of bioavailable and free testosterone. Subcutaneous adipose tissue correlated negatively with SHBG and positively with bioavailable estradiol adjusted for total testosterone. Both visceral adipose tissue and sc adipose tissue correlated inversely with total testosterone and DHT. Adjusting for SHBG, only visceral adipose tissue remained significantly correlated. Low total testosterone in viscerally obese men was not accompanied by increased LH. The androgen reference intervals were significantly displaced toward lower limits in obese vs. nonobese men (total testosterone: 8.5-29.3 vs. 12.5-37.6 nmol/liter; bioavailable testosterone: 6.1-16.9 vs. 7.6-20.7 nmol/liter; free testosterone: 0.23-0.67 vs. 0.29-0.78 nmol/liter; and DHT: 0.63-2.5 vs. 0.85-3.2 nmol/liter), whereas total estradiol (36.5-166 pmol/liter) and bioavailable estradiol (23.4-120 pmol/liter) reference intervals were not. In obese men, 22.9% had total testosterone less than 12.5 nmol/liter.

CONCLUSIONS

Visceral adipose tissues correlate independently with bioavailable and free testosterone in young men. The inverse relationship between total testosterone and sc adipose tissue seems to be accounted for by variations in SHBG. The reference intervals for total testosterone, bioavailable testosterone, free testosterone, and DHT are displaced toward lower limits in obese men.