{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T17:39:22Z","timestamp":1787506762732,"version":"build-2736575974"},"reference-count":12,"publisher":"Oxford University Press (OUP)","issue":"10","license":[{"start":{"date-parts":[[2019,8,28]],"date-time":"2019-08-28T00:00:00Z","timestamp":1566950400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100003182","name":"National Osteoporosis Foundation","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100003182","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["asbmr.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["JBMR Plus"],"published-print":{"date-parts":[[2019,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    In 2011, the International Osteoporosis Foundation and the International Federation of Clinical Chemistry and Laboratory Medicine selected serum collagen type\u2010I crosslinked C\u2010peptide (s\u2010CTX) as the reference standard for bone resorption. This study aimed to determine the within and between laboratory reproducibility for s\u2010CTX assays. To create standardized pools, serum was collected from 10 premenopausal and 10 postmenopausal women. Premenopausal sera were pooled to approximate a population with normal bone turnover; postmenopausal sera were pooled to approximate a population with high bone turnover; and a third pool was created from an equal proportion of the pre\u2010 and postmenopausal pools. Multiple identical aliquots from each pool were created and frozen; all were labeled as routine clinical specimens. To evaluate longitudinal laboratory reproducibility, an identical aliquot from each of the three pools was sent to four US commercial laboratories on five dates over a 6\u2010month period. To evaluate within\u2010run reproducibility, each lab received five identical aliquots from each pool on the fifth date. Three labs (Mayo, ARUP, and Quest) used the Roche Diagnostics Elecsys assay, and one (Esoterix\/LabCorp) used the IDS\u2010iSYS assay. Reproducibility was assessed using the coefficient of variation (CV) with 95% confidence intervals (CIs). Labs were unaware of the investigation. Across labs, mean s\u2010CTX values were 423, 533, and 480\u2009pg\/mL for the premenopausal, postmenopausal, and mixed pools, respectively, but the means differed between labs (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.001). The premenopausal pool longitudinal CVs ranged from 5.0% to 14.9%; the postmenopausal pool CVs ranged from 3.4% to 19.3%; and the mixed pool CVs ranged from 3.3% to 16.0%. The longitudinal reproducibility for Esoterix\/LabCorp was higher (CV 13.9%; 95% CI, 10.1% to 22.2%) than for the other labs. Within\u2010run CVs were also higher for Esoterix\/LabCorp (CV 8.6%; 95% CI, 6.3% to 13.6%) compared with the other labs (CVs 2.1% to 6.2%). In conclusion, the reproducibility of s\u2010CTX varied across US commercial labs, and was poorer for Esoterix\/LabCorp, which used the IDS assay, compared with the other three labs, which used the Roche assay. \u00a9 2019 The Authors.\n                    <jats:italic>JBMR Plus<\/jats:italic>\n                    published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.\n                  <\/jats:p>","DOI":"10.1002\/jbm4.10225","type":"journal-article","created":{"date-parts":[[2019,8,1]],"date-time":"2019-08-01T16:03:55Z","timestamp":1564675435000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Commercial Laboratory Reproducibility of Serum CTX in Clinical Practice"],"prefix":"10.1093","volume":"3","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3741-4034","authenticated-orcid":false,"given":"Sahar M","family":"Hindi","sequence":"first","affiliation":[{"name":"Division of Endocrinology Medical Subspecialties Institute, Cleveland Clinic Abu Dhabi Abu Dhabi United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric","family":"Vittinghoff","sequence":"additional","affiliation":[{"name":"Department of Epidemiology and Biostatistics University of California, San Francisco San Francisco CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4750-9125","authenticated-orcid":false,"given":"Anne L","family":"Schafer","sequence":"additional","affiliation":[{"name":"Department of Epidemiology and Biostatistics University of California, San Francisco San Francisco CA USA"},{"name":"Medical Service Endocrinology and Metabolism Section, San Francisco Veterans Affairs Health Care System San Francisco CA USA"},{"name":"Department of Medicine, Division of Endocrinology and Metabolism University of California, San Francisco San Francisco CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stuart","family":"Silverman","sequence":"additional","affiliation":[{"name":"Cedars Sinai Medical Center UCLA School of Medicine Los Angeles CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5261-7721","authenticated-orcid":false,"given":"Douglas C","family":"Bauer","sequence":"additional","affiliation":[{"name":"Department of Epidemiology and Biostatistics University of California, San Francisco San Francisco CA USA"},{"name":"Department of Medicine, Division of General Internal Medicine University of California, San Francisco San Francisco CA USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2019,8,28]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00223-014-9842-y"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.1515\/CCLM.2011.602"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00198-010-1501-1"},{"key":"e_1_2_7_5_1","doi-asserted-by":"publisher","DOI":"10.1359\/jbmr.091006"},{"key":"e_1_2_7_6_1","doi-asserted-by":"publisher","DOI":"10.1359\/JBMR.040512"},{"key":"e_1_2_7_7_1","doi-asserted-by":"publisher","DOI":"10.1186\/1479-5876-11-201"},{"key":"e_1_2_7_8_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00198-012-2049-z"},{"issue":"8","key":"e_1_2_7_9_1","doi-asserted-by":"crossref","first-page":"1443","DOI":"10.1093\/clinchem\/47.8.1443","article-title":"Interlaboratory variation of biochemical markers of bone turnover","volume":"47","author":"Seibel MJ","year":"2001","journal-title":"Clin Chem."},{"key":"e_1_2_7_10_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00198-009-0974-2"},{"issue":"1","key":"e_1_2_7_11_1","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1080\/00031305.1996.10473537","article-title":"Confidence intervals for a normal coefficient of variation","volume":"15","author":"Vangel MG","year":"1996","journal-title":"Am Stat."},{"key":"e_1_2_7_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/(SICI)1097-0258(19960330)15:6<647::AID-SIM184>3.0.CO;2-P"},{"key":"e_1_2_7_13_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00198-017-4082-4"}],"container-title":["JBMR 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