title: New biochemical markers of bone resorption derived from collagen breakdown in the study of postmenopausal osteoporosis.
abstract: The aim of this work was to perform a comparative study between three recently developed biochemical markers of bone resorption derived from collagen metabolism--(1) total urinary free pyridinolines (Pyr), (2) serum pyridinoline cross-linked carboxy-terminal telopeptides of type I collagen (ICTP) and (3) a urinary-specific sequence for a part of the C-telopeptide of the alpha 1 chain of type I collagen (CTX)--in the diagnosis and follow-up of postmenopausal osteoporosis. Results were also evaluated relative to the classical biochemical marker urinary hydroxyproline (Hyp). The study included 20 untreated osteoporotic postmenopausal women (OSP), age 60 +/- 6 years, range 46-69 years; 27 osteoporotic postmenopausal women treated (OSP-T) by cyclic therapy with disodium etidronate, 25-hydroxyvitamin D and calcium for a period between 3 months and 4 years (25 +/- 15 months), age 59 +/- 7 years, range 41-67 years; 17 osteopenic postmenopausal women, age 57 +/- 6 years, range 46 +/- 68 years; and 29 healthy control postmenopausal women, age 56 +/- 7 years, range 41-70 years. The diagnostic criterion for postmenopausal osteoporosis was a bone mineral density (BMD) (Hologic QDR-1000) in lumbar spine and/or femoral neck more than 2 SD below the mean value corresponding to an age- and sex-matched healthy control group. For inclusion in the osteopenic group BMD values had to be between 1 and 2 SD below the mean BMD value corresponding to the control group. We found a significant increase (p < 0.01) in the levels of Pyr/Cr and CTX/Cr (Cr = creatinine) in OSP patients with respect to the control group and we did not observe any significant difference between control and OSP-T or osteopenic women. It is interesting to note that there was a mean increase in CTX/Cr in OSP patients of 101% of the control values, while the mean increase found in Pyr/Cr concentration was only 33%. However, we did not find significant differences in the concentrations of ICTP and Hyp/Cr between groups. In a comparison of Pyr/Cr and CTX/Cr, urinary CTX showed the higher diagnostic accuracy, as can be deduced from the receiver operating characteristic (ROC) curves. CTX sensitivity was 40% with a specificity of 100%, whereas the sensitivity was 25% for urinary Pyr/Cr. In conclusion, the results of the present work suggest that in osteoporotic women CTX has the highest diagnostic accuracy among the markers of bone resporption studied.
authors.affiliation: Servicio de Bioquimica Clinica, Laboratorio de Metabolismo Mineral y Oseo, Madrid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Guerrero
authors.forename: M A
authors.initials: MA
authors.lastname: Diaz Martin
authors.forename: E M
authors.initials: EM
authors.lastname: Diaz Diego
authors.forename: T
authors.initials: T
authors.lastname: Disla
authors.forename: A
authors.initials: A
authors.lastname: Rapado
authors.forename: C
authors.initials: C
authors.lastname: de la Piedra
mesh_terms: D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000097:blood / Q000652:urine; D015415:Biomarkers; D001851:Bone Diseases, Metabolic / Q000378:metabolism; D001862:Bone Resorption; D002118:Calcium / Q000627:therapeutic use; D003094:Collagen / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D012968:Etidronic Acid / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000627:therapeutic use; D006909:Hydroxyproline / Q000652:urine; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism*; D010446:Peptide Fragments / Q000097:blood / Q000737:chemistry; D012016:Reference Values
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D006887:Hydroxycholecalciferols; D010446:Peptide Fragments; C015484:pyridinoline; D003094:Collagen; D012968:Etidronic Acid; D006909:Hydroxyproline; D002118:Calcium