Inverse association between bone turnover rate and bone mineral density incommunity-dwelling men > 70 years of age: No major role of sex steroid status

Bone loss is accelerated in elderly men. Little is known about the pathophy siology of senile bone loss or about the role played by relative sex steroi d deficiency in the determination of bone turnover in elderly men. In a pop ulation-based sample of 283 healthy, ambulatory men, aged 71-86 years, we s ought to determine whether lower bone mineral density (BMD; using dual-ener gy X ray absorptiometry at the hip and the forearm) is associated with high er bone turnover, and we assessed the impact of sex steroid status on bone turnover. Indices of bone formation, serum osteocalcin (s-Oc), and bone-spe cific alkaline phosphatase (s-bAP) and indices of bone resorption, serum an d urinary telopeptide of type I collagen (s-CTx and u-CTx), and urinary fre e deoxypyridinoline (u-Dpd) were intercorrelated (r = 0.29-0.76, p < 0.001) . Bone turnover indices were negatively associated with BMD (r = -0.17 to - 0.34, p < 0.01). In univariate analyses, there was a trend toward weak nega tive associations of bone turnover markers with serum free testosterone (FT ), significant only for s-Oc and s-CTx (r = -0.16 and -0.14, p < 0.01), and with serum free estradiol (FE2), significant only for u-CTx and s-CTx (r = -0.18 and -0.19; p < 0.01). The lower quartile for FE2 was associated with higher values of u-CTx (p = 0.003) and s-CTx (p < 0.001). However, in mult ivariate models, for the individual markers of bone turnover a negative ass ociation between estradiol (E-2) or FE2 and s-CTx was the only remaining (m arginally) significant association (p < 0.05) for the relationship between sex steroids and any of the bone turnover indices assessed. In community-dw elling men age >70 years, bone turnover rate, as determined by biochemical markers, is a significant negative determinant of prevalent BMD. However, t he findings do not support the view that relative differences in sex steroi d status, as observed among healthy elderly men, have a major impact on bon e turnover. (Bone 29:286-291; 2001) (C) 2001 by Elsevier Science Inc. All r ights reserved.