Age-related changes in sex steroid levels influence bone mineral density in healthy Indian men

Age-related changes in sex steroid levels and its contribution to variations in rate of bone loss among men is unclear. Although, Bio-T and Bio-E-2 levels declined with age and depicted an association with BMD in healthy Indian men, Bio-E-2 was found to be an independent predictor of BMD. Ethnicity influences sex steroid levels, therefore, their role in pathogenesis of low bone mass needs to be established in various populations. We assessed the extent of changes in sex steroid levels with age and related these to bone mineral density (BMD) in healthy Indian men. Total testosterone (TT), estradiol (E-2), sex hormone-binding globulin (SHBG), PTH, osteocalcin (OC), and c-terminal telopeptide (CTX) were measured in 330 men aged 20-55 years and correlated with BMD measured by DXA. Both Bio-T (1% per year) and Bio-E-2 (0.8% per year) levels decreased significantly in ageing men, whereas TT (0.4% per year) and E-2 (0.3% per year) levels decreased only marginally with age. In contrast, SHBG (1.4% per year) and PTH (1% per year) levels increased significantly with age. Serum TT (r = 0.19, p = 0.01) and Bio-T (r = 0.2, p = 0.01) levels were associated positively with BMD at spine, whereas E-2 and Bio-E-2 levels were associated with BMD at spine [E (2) (r = 0.31, p < 0.0001); Bio-E-2 r = 0.37, p < 0.0001] and femur (E-2 r = 0.26, p = 0.001; Bio-E-2 r = 0.27, p = 0.001). Men in the lowest quartile of Bio-E-2 were associated with lower BMD and higher bone turnover. Age-related decrease in bioavailable sex steroid levels is associated with BMD in healthy Indian men. Bio-E-2 was found to be an independent predictor of BMD.