Endogenous sex steroids and bone mineral density in healthy men.

Objective: To evaluate the role of endogenous sex steroids on bone mineral density (BMD) in healthy Turkish men.

Methods: Serum total testosterone (TT), free testosterone (FT), dehydroepiandrosterone sulfate and estradiol levels were assayed in 174 healthy men of 240 volunteers, aged 22-76 years. Dual-energy X-ray absorptiometry was used to measure the BMD (g/cm(2)) of lumbar spine, femoral neck and non-dominant proximal and distal radius-ulna sites. Linear regressions were conducted using each BMD site as the dependent variable and each sex steroid as the independent variable. Four models were run for each bone site and sex steroid; crude, age-adjusted, adjusted for age and body mass index (BMI), and adjusted for age, BMI and cigarette-smoking.

Results: The mean age and BMI of men enrolled in the study were 47.7 +/- 13.7 years and 26.9 +/- 3.6 kg/m(2). Log of FT was significantly associated with the BMD of distal forearm in all models analyzing the crude and adjusted effects. Dehydroepiandrosterone sulfate effect on BMD of proximal forearm came closer to the level of statistical significance when adjusted with age, BMI and cigarette-smoking. Estradiol and TT levels were not found to be associated with BMD of any sites measured.

Conclusion: Among the endogenous sex steroids in men, predominantly FT seems to be one of the determinants of BMD. Therefore a decrease in serum levels of testosterone in aging male or secondary causes may negatively affect BMD.