Hormonal and biochemical parameters in the determination of osteoporosis in elderly men

The extent to which changes in several hormonal and biochemical parameters are involved in the pathogenesis of osteoporosis in men remains controversial. This study examined the roles of free testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), 25-hydroxyvitamin D, PTH, and insulin-like growth factor I in the determination of bone mineral density (BMD) in 437 community-dwelling elderly men. Age, height, weight, quadriceps strength, and femoral neck (FN) and lumbar spine (LS) BMD were also obtained. In multiple regression analysis, after adjusting for age and weight, low E2 (P = 0.01), and high SHBG (P = 0.0002) levels were common determinants of FN and LS BMD. In addition, high PTH (P = 0.03) was an independent predictor of FN BMD, and low free T (P = 0.02) was an independent predictor of LS BMD. Low free T was associated with FN BMD in univariate analysis only. The hormonal measurements collectively accounted for 5% and 7% of the age- and weight-adjusted variance of FN and LS BMD, respectively. The sex steroids, SHBG and insulin-like growth-I were found to be interrelated using a technique of path analysis that examines the intercorrelation between these variables. A subject with any one abnormal serum parameter had a 4-fold increase in the risk of osteoporosis, whereas three abnormal parameters were associated with an 11-fold increased risk, although the latter group only applied to 1% of the study population. Although the precise causal effects these biochemical parameters may have on the development of osteoporosis remains to be determined, the present findings support an important interrelated role for these hormonal and biochemical parameters on changes in bone density in elderly men.