| Objective To study the associations of serum levels Type I collagen carboxy-terminal peptide (CTX-1), Tartrate resistant acid phosphatase (TRACP), Bone specific alkaline phosphatase (BALP) and Osteocalcin (OC) with lumbar spine BMD in 30 to 79 year-old healthy individuals stratified by age and gender. Methods Lumbar spine BMD (L1-4) was measured by Hologic Discovery WA bone mineral densitometer, and enzyme immunoassay analyzer was used to measure the levels of bone remodelling markers( CTX-1，TRACP, BALP and OC)in the serum. The 1228 participants were grouped according to gender and age (per 10 years). SPSS 19. 0 was used for statistical analysis. Results In females, the levels of CTX-1，TRACP, BALP and OC had no significant correlation with lumbar spine BMD in the 30-49 age groups; CTX-1 and TRACP increased significantly and had negatively correlation with lumbar spine BMD after the age of 50; levels of BALP and OC increased significantly and had negatively correlation with BMD in the 50 -59 age group, then began to decline and were positively correlated with BMD after the age of 60. In males, the levels of CTX-1, TRACP and BALP had no significant correlation with lumbar spine BMD in the 30-59 age groups, but CTX-1，TRACP, BALP increased significantly and were negatively correlated with BMD after the age of 60. The level of OC declined gradually with age, but had no significant correlation with BMD in all age groups in male. The measure values of TRACP, CTX-1, BALP and OC were not signiticantly different between males and females in the 30-49 age groups, but different significantly between males and females in the same age group after the age of 50 (P < 0. 05)，with the measures values in females higher than those of males. Conclusion TRACP, CTX-1, BALP, OC are important markers for monitoring changes in bone metabolism, in particular, they have high sensitivity and specificity for osteoporosis in female. |