[Smoking & Bone.]

Smoking is associated with decreased bone mineral density(BMD)and increased fracture risk. Conversely, smoking cessation results in BMD gain and decreased fracture risk, suggesting that smoking-induced bone metabolic changes are partially reversible. However, the mechanism of bone fragility induced by smoking is unknown. Meta-analyses have shown that aberrant PTH-vitamin D axis may affect bone metabolism in smokers. Previous animal studies have also reveled that nicotine, one of the major toxic substances of cigarettes, negatively regulates bone formation. This brief review will summarize recent studies on the effects of smoking on bone metabolism, including our recent results evaluating bone metabolic changes after smoking cessation.