title: Age-related changes of serum bone alkaline phosphatase and cross-linked C-telopeptides of type I collagen and the relationship with bone mineral density in Chinese women.
abstract: BACKGROUND
  Previous studies have shown that bone turnover rate changes with age. At the same time, there is no definitive research regarding age-related changes of bone turnover level and its association with bone mineral density (BMD) in Chinese mainland women.
  
  
  METHODS
  In a cohort of 663 Chinese mainland women aged 20-70 years, serum bone alkaline phosphatase (BAP) and serum cross-linked C-telopeptides of type I collagen (sCTX) were measured to evaluate the state of bone formation and resorption, respectively. BMD was measured in the posteroanterior spine, supine lateral spine, hip and forearm using a dual-energy X-ray absorptiometry.
  
  
  RESULTS
  The cubic polynomial regression model best fit age-related changes in serum BAP (R2=0.398, p<0.001) and sCTX concentrations (R2=0.148, p<0.001) with largest R2 from comparison 8 different regression models. Their values reached a minimal level in the 30-39 years age group, and increased dramatically in the 40-59 years groups. There was a decreasing trend of BAP in women >60 years. The levels of BAP and sCTX were inversely correlated to BMD in various skeletal regions over the entire population (r=-0.096 to -0.357, p<0.05). sCTX was a significant predictor of a T-score< or =-2.5 of BMD in postmenopausal women with sCTX levels above mean+2 SD of women aged 30-39 years compared with other postmenopausal women, which indicated by odds ratios 1.9-3.7 (p<0.05) for various skeletal regions, especially for the lateral lumbar spine (2.2, p<0.01), Ward's triangle (3.7, p<0.01), and ultradistal end of radius + ulna (2.8, p<0.001).
  
  
  CONCLUSIONS
  Age-dependent serum BAP and sCTX were inversely correlated to BMD, and sCTX was a useful parameter for the prediction of a low T-score of BMD at skeletal sites with abundant cancellous bone in postmenopausal women.
authors.affiliation: Institute of Endocrinology and Metabolism, the Second Xiang-Ya Hospital, Central South University, Changsha, 86 Renmin-Zhong Rd, Hunan 410011, PR China.
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Shan
authors.forename: Xian-ping
authors.initials: XP
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Xiang-hang
authors.initials: XH
authors.lastname: Luo
authors.forename: Xing-Zhi
authors.initials: XZ
authors.lastname: Cao
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.forename: Shi-Ping
authors.initials: SP
authors.lastname: Liu
authors.forename: Yin-Zheng
authors.initials: YZ
authors.lastname: Pi
authors.forename: Tuan-Yu
authors.initials: TY
authors.lastname: Fang
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Zhi-Heng
authors.initials: ZH
authors.lastname: Chen
authors.forename: Ni
authors.initials: N
authors.lastname: Zhong
authors.forename: Er-Yuan
authors.initials: EY
authors.lastname: Liao
mesh_terms: D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood*; D015519:Bone Density; D001842:Bone and Bones / Q000201:enzymology / Q000378:metabolism; D002681:China; D024042:Collagen Type I / Q000097:blood*; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D010455:Peptides / Q000097:blood*
chemical_list: D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D000469:Alkaline Phosphatase