title: Chinese bone turnover marker study: reference ranges for C-terminal telopeptide of type I collagen and procollagen I N-terminal peptide by age and gender.
abstract: BACKGROUND
  Bone formation marker procollagen I N-terminal peptide (PINP) and resorption marker C-terminal telopeptide of type I collagen (β-CTX) are useful biomarkers for differential diagnosis and therapeutic evaluation of osteoporosis, but reference values are required.
  
  
  METHODS
  The multi-center, cross-sectional Chinese Bone Turnover Marker Study included 3800 healthy volunteers in 5 Chinese cities. Serum PINP, β-CTX, parathyroid hormone (PTH) and 25OHD levels were measured by chemiluminescence assay. Lumbar spine and proximal femur BMD were measured by dual-energy X-ray absorptiometry. Serum PINP and β-CTX levels were assessed by age, gender, weight, recruitment latitude, levels of PTH and 25OHD.
  
  
  RESULTS
  Subjects (n = 1436, M:F, 500:936; mean age 50.6 ± 19.6 years) exhibited non-normally distributed PINP and β-CTX peaking between 15-19 years, gradually declining throughout adulthood, elevating within 10 years of postmenopause, and then declining by age 70. In women between the age of 30 and menopause, median PINP and β-CTX levels were 40.42 (95% CI: 17.10-102.15) and 0.26 (95% CI: 0.08-0.72) ng/mL, respectively. β-CTX and PINP were positively linearly correlated (r = 0.599, P<0.001). β-CTX correlated positively (r = 0.054 and 0.093) and PINP correlated negatively (r =  -0.012 and -0.053) with 25OHD and PTH (P<0.05).
  
  
  CONCLUSIONS
  We established Chinese reference ranges for PINP and CTX. Chinese individuals exhibited high serum PINP and β-CTX levels between 15 and 19 years of age and at menopause, which gradually declined after 70 years of age.
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Laboratory, People's Hospital, Hubei Province, Wuhan, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Geriatrics, General Hospital of Guangzhou Military Command, Guangzhou, China.
authors.forename: Weimin
authors.initials: W
authors.lastname: Deng
authors.affiliation: Department of Osteoporosis, Sixth People's Hospital, Shanghai Jiaotong University, Shanghai, China.
authors.forename: Zhenlin
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, Second Affiliated Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Endocrinology, Key Laboratory of Endocrinology of Ministry of Health, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Weibo
authors.initials: W
authors.lastname: Xia
authors.affiliation: Department of Obstetrics and Gynecology, Chinese Academy of Medical Sciences, Peking Union Medical College, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000531:Altitude; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D001835:Body Weight; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism*; D002112:Calcifediol / Q000097:blood; D002681:China; D024042:Collagen Type I / Q000097:blood / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010446:Peptide Fragments / Q000097:blood / Q000378:metabolism*; D010455:Peptides / Q000097:blood / Q000378:metabolism*; D011347:Procollagen / Q000097:blood / Q000378:metabolism*; D012016:Reference Values; D055815:Young Adult
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; D002112:Calcifediol