title: Urinary cross-linked N-telopeptides of type I collagen and bone metabolic diseases.
abstract: OBJECTIVE
  To evaluate the type I collagen cross-linked N-telopeptide (NTx) levels in human urine as an indicator of bone resorption rate in different ages, sex and in bone metabolic diseases.
  
  
  METHODS
  Urinary NTx was determined by immunoassay in 591 Beijing healthy subjects aged from 0 to 86 years and 379 patients with bone metabolic diseases.
  
  
  RESULTS
  The levels of urinary NTx were significantly higher in children than in adults (P < 0.001) and higher in boys than in girls (P < 0.01) and increased 1.4-2.2 times in postmenopausal females than in men and premenopausal women. Urine NTx had a positive linear correlation with urine HOP/Cr (r = 0.778, P < 0.01) and Ca/Cr ratio (r = 0.320, P < 0.01), and a negative linear correlation with age (r = -0.523, P < 0.01) and lumbar spine BMD (r = -0.426, P < 0.01). The levels of urine NTx increased for 3.6 times in pregnancy, 1.5 times in osteoporosis, 1.9 times in fragility fracture, 3.6 times in chronic renal failure, 2.1 times in rickets and 7.2 times in multiple myeloma compared to age matched controls.
  
  
  CONCLUSIONS
  NTx in urine is a specific and sensitive indicator of bone resorption and is able to distinguish normal premenopause from late osteoporotic patients. NTx could be used as diagnostic information about metabolic bone diseases, and to monitor antiresorptive therapy.
authors.affiliation: Department of Biochemistry, Beijing Jishuitan Hospital, Beijing 100035, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Xue
authors.forename: W
authors.initials: W
authors.lastname: Jia
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Dong
authors.forename: J D
authors.initials: JD
authors.lastname: Clemens
authors.forename: X
authors.initials: X
authors.lastname: Tian
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D001862:Bone Resorption / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000652:urine*; D024042:Collagen Type I; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000652:urine*; D010455:Peptides / Q000652:urine*; D011247:Pregnancy; D012737:Sex Factors
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen