Bone Metabolism: Effects of Essential and Toxic Trace Metals

Osteoporosis is an insidious disease prevalent mainly in the elderly, particularly postmenopausal women. While the detailed etiology remains to be determined, the underlying mechanism appears to be an imbalance between osteoblast-dependent bone matrix formation, which is coupled to mineralization, and osteoclast-dependent bone resorption, resulting in a net bone loss. The literature on Ca dynamics is legion, but leads inevitably to the conclusion that manipulation of Ca levels alone does not optimally counteract the progress of the disease (Bronner. 1994). While Ca is the major mineral of bone matrix, other essential and xenobiotic metals not only deposit in the matrix, but have specific, dose-dependent effects on bone cell function that may play major roles in the balance between osteoblast and osteoclast activities. This chapter focuses on some essential and xenobiotic metals that have been found to have just such a direct effect on bone cell function.