慢性閉塞性肺疾患

Secondary osteoporosis. Chronic obstructive pulmonary disease：COPD.

　COPDは長期の喫煙が主因となる肺の炎症性疾患だが，全身性疾患でもあり，骨粗鬆症や虚血性心疾患，サルコペニアなどの様々な肺外併存症を合併する。代表的な合併症である骨粗鬆症の有病率は非常に高く，比較的症状に乏しい時期から椎体骨折を高率に認める。COPDの骨脆弱性には骨密度低下とともに骨質の劣化が関与するが，骨代謝異常の機序については明らかになっていない。COPDでは，一般的な骨折リスク因子に加え，全身性炎症やステロイド使用，ビタミンＤ不足・欠乏などの疾患特異的な骨折リスク因子が多く集積している。COPD患者の骨折を防止するために，ビタミンＤの充足とともに積極的な骨粗鬆症に対する薬物治療が望まれる。

　Chronic obstructive pulmonary disease（COPD）, an inflammatory disease of the lung mainly caused by cigarette smoking, is a systemic disease associated with various extra-pulmonary comorbidities such as osteoporosis, ischemic heart disease and sarcopenia. Osteoporosis is one of such complications, and the prevalence of vertebral fractures in COPD is high even in early COPD stages. Loss of bone mineral density as well as deterioration of bone quality is common in COPD patients. However, the pathophysiology of bone fragility in COPD-associated osteoporosis is still incompletely understood. COPD patients are exposed to various disease-specific risk factors such as systemic inflammation, glucocorticoid use and vitamin D insufficiency/deficiency, accumulation of which leads to development of COPD-associated osteoporosis. Vitamin D repletion and timely intervention with anti-osteoporotics would be important to protect COPD patients from fracture.