title: [Biochemical markers of age-related changes in bones turnover and bone mineral density in healthy Chinese men].
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Nursing, Central South University, Changsha 410013, China.
authors.forename: Yue-xia
authors.initials: YX
authors.lastname: Jiang
authors.forename: Si-yuan
authors.initials: SY
authors.lastname: Tang
authors.forename: Xian-ping
authors.initials: XP
authors.lastname: Wu
authors.forename: Ling-feng
authors.initials: LF
authors.lastname: Yang
authors.forename: Er-yuan
authors.initials: EY
authors.lastname: Liao
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000378:metabolism*; D015415:Biomarkers; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism*; D024042:Collagen Type I / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000517:prevention & control; D010455:Peptides / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D000469:Alkaline Phosphatase