OBJECTIVE: To determine the relationship between bone alkaline phosphatase (BAP) and cross-linked N-telopeptides of type I collegen(NTX) and bone mineral density in healthy men aged 20-80. METHODS: BAP and NTX of 389 healthy men were measured by ELISA. BMD at the lumbar spine and the hip as measured by dual energy X-ray absorptiometry. The correlation of bone biochemical markers with age and BMD fit 10 regression models. RESULTS: BAP and NTX negatively correlated with age. The cubic regression model was better with age-related changes of bone biochemical markers as compared with the other regression models and the coefficients of determination of fitting curve were 0.013-0.029 (P< 0.05). The value of bone biochemical markers as the highest during 20-29 age groups, then they decreased to a nadir level in the 50-59 years age. After 60 years, bone formation markers remained stable; however resorption marker increased slightly. After adjustment for age, weight, height, BMI, and smoking, bone biochemical markers were negatively correlated with most sites of BMD. CONCLUSION: BAP and NTX may be relatively sensitive and specific markers to evaluate age-related changes of bone turnover. It may benefit the prevention of osteoporosis by monitoring the level of BAP and NTX.
OBJECTIVE: To determine the relationship between bone alkaline phosphatase (BAP) and cross-linked N-telopeptides of type I collegen(NTX) and bone mineral density in healthy men aged 20-80. METHODS:BAP and NTX of 389 healthy men were measured by ELISA. BMD at the lumbar spine and the hip as measured by dual energy X-ray absorptiometry. The correlation of bone biochemical markers with age and BMD fit 10 regression models. RESULTS:BAP and NTX negatively correlated with age. The cubic regression model was better with age-related changes of bone biochemical markers as compared with the other regression models and the coefficients of determination of fitting curve were 0.013-0.029 (P< 0.05). The value of bone biochemical markers as the highest during 20-29 age groups, then they decreased to a nadir level in the 50-59 years age. After 60 years, bone formation markers remained stable; however resorption marker increased slightly. After adjustment for age, weight, height, BMI, and smoking, bone biochemical markers were negatively correlated with most sites of BMD. CONCLUSION:BAP and NTX may be relatively sensitive and specific markers to evaluate age-related changes of bone turnover. It may benefit the prevention of osteoporosis by monitoring the level of BAP and NTX.