title: C-telopeptides of type I collagen in postmenopausal women: an experience in a Tunisian clinical laboratory.
abstract: OBJECTIVE
  The purpose of study was to evaluate the interest of C-telopeptides of type I collagen (CTX) in the diagnosis of osteoporosis in postmenopausal women and to define its cut-off value.
  
  
  METHODS
  A transverse descriptive study enrolled postmenopausal women: 139 osteoporotic (G1) and 39 non osteoporotic (G2). The 2 groups were defined by bone density measurement. The following markers were measured: serum alkaline phosphatase (ALP), bone alkaline phosphatase (bone ALP), serum C-terminal telopeptide of type I collagen (CTX). Statistical analyses were performed using SPSS 10.5. The corresponding estimation of sensitivity and specificity of CTX have been presented as 'receiver Operating Curve' (ROC).
  
  
  RESULTS
  There was no difference in the measurement of ALP and bone ALP in the 2 groups but CTX was statistically higher in G1 compared to G2 (p <0.001). The percentage of osteoporotic women (G1) with CTX values > 0.500 ng/ml was higher than that of non osteoporotic women (G2). We have established a ROC curve to find the cut-off value of CTX that enables the distinction between osteoporotic women with high level of bone remodelling, and non osteoporotic women. The cut-off value of CTX 0.55 pg/ml was the best; it associated best sensitivity and specificity.
  
  
  CONCLUSIONS
  The total increase and significance for CTX was greater in the group of osteoporotic women and appeared therefore to be a good bone turnover marker in the diagnosis of osteoporosis in comparison with ALP and bone ALP. The cut-off value of CTX 0.55 pg/ml may improve the sensitivity and specificity of prediction of future fractures.
authors.affiliation: Laboratory of Clinical Biochemistry, Charles Nicolle Hospital - Tunis.
authors.forename: Kahena
authors.initials: K
authors.lastname: Bouzid
authors.forename: Afef
authors.initials: A
authors.lastname: Bahlous
authors.forename: Eya
authors.initials: E
authors.lastname: Kalaï
authors.forename: Hayet
authors.initials: H
authors.lastname: Fellah
authors.forename: Hela
authors.initials: H
authors.lastname: Sahli
authors.forename: Slaheddine
authors.initials: S
authors.lastname: Sellami
authors.forename: Jaouida
authors.initials: J
authors.lastname: Abdelmoula
mesh_terms: D015415:Biomarkers / Q000097:blood; D024042:Collagen Type I / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D010024:Osteoporosis / Q000097:blood* / Q000175:diagnosis*; D010455:Peptides / Q000097:blood*; D017698:Postmenopause
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide