Chronic obstructive pulmonary disease severity in middle-aged and older men with osteoporosis associates with decreased bone formation

Chronic obstructive pulmonary disease (COPD) is a risk factor for osteoporosis. Nevertheless, much remains unclear regarding the bone metabolism dynamics associated with COPD. The present study focuses on the associations between the COPD severity and serum bone metabolism biomarkers. We enrolled 40 patients who visited the orthopedics departments at our institutions and underwent dual-energy X-ray absorptiometry between September 2015 and December 2017. Only male osteoporosis patients over 45 years of age were included, and 5 patients were excluded due to disease or use of internal medicines affecting bone metabolism. All subjects underwent lung function testing, spine radiography, and blood tests. We measured percent forced expiratory volume in 1 second (%FEV1), which reflects COPD severity, and we examined the relationships between %FEV1 and serum levels of bone metabolism biomarkers. All subjects were diagnosed with osteoporosis based on T-scores. %FEV1 correlated with body weight, body mass index (BMI), and Z-score/T-scores. %FEV1 moderately correlated with serum levels of alkaline phosphatase (ALP), procollagen type 1 N-terminal propeptide (P1NP), and tartrate-resistant acid phosphatase 5b in the partial correlation analysis adjusted for BMI or T-score in the lumbar vertebrae. We performed a hierarchical multiple regression analysis to identify that serum ALP and P1NP were the independent explanatory variables to %FEV1 independent of other factors. The data suggest that the COPD severity in middle-aged and older men with osteoporosis associates with decreased bone formation. COPD patients may exhibit bone metabolism dynamics characterized by low bone turnover with osteogenesis dysfunction as COPD becomes severe.