The relationship between blood mercury level and osteoporosis in postmenopausal women

Objective: Postmenopausal women have a higher prevalence of osteoporosis compared with premenopausal women. Postmenopause status has been found to be an independent risk factor for osteoporosis. Several studies have reported that heavy metals, including lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As), have detrimental effects on bone. The aim of this study was to evaluate the association among heavy metals, including Pb, Hg, Cd, and As, bone mineral density, and osteoporosis in postmenopausal Korean women. Methods: We conducted a cross-sectional study of 481 postmenopausal women, all of whom were enrolled in the Korean National Health and Nutrition Examination Survey in 2008. Bone mineral density was measured using dual-energy x-ray absorptiometry. Blood Pb, Hg, and Cd and urinary As levels were measured. Results: Postmenopausal women with higher blood Hg levels were more likely to be younger and have higher vitamin D levels, fish consumption, and prevalence of osteoporosis. On multivariate logistic regression analysis, postmenopausal women with blood Hg levels in the fourth quartile had a 0.36-fold decreased risk of having osteoporosis compared with those with levels in the first quartile, after adjustments for age, body mass index, alcohol intake, smoking history, exercise, use of oral contraceptive pills, hormone therapy, intake of caloric energy and calcium, fish consumption, and vitamin D level. However, there was no association between other heavy metals and osteoporosis. Conclusions: High blood Hg levels were associated with a lower risk of having osteoporosis in postmenopausal women. Because biomarkers of all four metals measured in this study reflect recent exposures, further studies are necessary to clarify the association of osteoporosis with the level of heavy metals in biomarkers for long-term exposure such as hair or fingernail.