Bone mass density selectively correlates with serum markers of oxidative damage in post-menopausal women

Background: Post-menopausal osteoporosis (PO) affecting a large fraction of elderly women, is triggered by the decline in 17 beta-estradiol (E2) level. Experimental studies in animal models and cell cultures have suggested that the fall in E2 might contribute to developing oxidative stress (OS) which in turn is believed to play an important role in PO pathogenesis. The scarcity of human studies focusing on this issue prompted us to investigate the effects of the reproductive and post-reproductive phase of women's life on OS and bone health. Methods: Serum parameters of oxidative challenge (lipid hydroperoxides and protein advanced oxidation products) and antioxidant defence (total serum antioxidants levels) along with bone mineral density (BMD) at femoral neck and lumbar spine were assessed in a sample of 191 women (98 pre- and 93 post-menopausal, of whom 30 osteoporotic). Results: Pearson's correlation analysis unveiled that spinal BMD was negatively correlated with lipid hydroperoxides in overall postmenopausal subsample (r=-0.251, p=0.012), while no significant link between these two variables was detected in women in reproductive age (r=-0.022, p=0.833). Noteworthy, stepwise multiple regression analysis showed that the association found in post-menopausal women retained significance after adjusting for potential confounding factors (p=0.001). Conclusions: Our data showed that markers of oxidative challenge are associated with bone loss in women in postmenopausal status. We suggest that menopause-related estrogen withdrawal might contribute to make bone more vulnerable to oxidative injury thereby increasing the risk of PO development.