Age-related changes in bone mineral density in Japanese adult males: association with bone metabolic markers *
In contrast to females, age-related changes in bone mineral density（BMD）in males, particularly in Japanese males, have not been thoroughly investigated. In this study, I investigated age-related changes in BMD in Japanese adult males in association with bone metabolic markers. The subjects were Japanese adult males who underwent bone densitometry during health check-ups in our hospital between 1989 and 2005. Among a total of 1737 subjects, 443 subjects underwent more than twice in different years. The mean age at the first visit was 54.3±10.4 years old, and the duration between the first and last visit was 4.8 years on average. Bone densitometry was performed at the lumbar spine, radius, and femoral neck by dual X-ray absorptiometry. The BMD results at the first visit were used for a cross-sectional analysis and the BMD changes between the first and last visit for a longitudinal analysis. From 39 to 71 subjects were selected from the subjects for the longitudinal analysis, and their urine and blood samples were analyzed for bone metabolic markers. Any history of fragility fracture was assessed by interview and thoracolumbar X-ray. In the cross-sectional study, both radial and femoral neck BMD showed a significant negative correlation with age（r＝-0.377 and -0.224, respectively）, whereas no significant correlation was found between the lumbar BMD and age. The annual change in BMD was 0.405±1.56％ for the lumbar spine, -0.249±1.12 for the femoral neck, and -0.517±0.89％ for the radius（p＜0.001 for all）. Among the bone metabolic markers evaluated, urinary deoxypyridinoline significantly correlated with the annual BMD changes at the lumbar spine and femoral neck（r＝-0.323 and -0.439, respectively）. Four cases of incident fragility fractures were recorded, but no significant relationship was found between the fracture occurrence and bone metabolic markers. In conclusion, lumbar BMD shows an age-related increase in many cases of elderly males and a careful assessment of BMD is required in diagnosing male osteoporosis. The results suggest that the increased markers of bone resorption could be used to predict future bone loss as in the case in females. (Accepted on October ３，2006)
