ECEESPE2025 ePoster Presentations Bone and Mineral Metabolism (142 abstracts)
Evaluation of a new IDS beta crosslaps® (CTX-I) assay for the iSYS automated analyzer
Michael Schønemann Rand 1,2 , Jutarat Charoenpatrawut 1 , Lasse Kristoffer Bak 1,2,3 , Etienne Cavalier 4 & Niklas Rye Jørgensen 1,2,5
1Rigshospitalet, Department of Clinical Biochemistry, Glostrup, Denmark; 2Rigshospitalet, Translational Research Centre, Glostrup, Denmark; 3University of Copenhagen, Department of Drug Design and Pharmacology, Copenhagen, Denmark; 4University of Liege, Department of Clinical Chemistry, Liège, Belgium; 5University of Copenhagen, Faculty of Health and Medical Sciences, Department of Clinical Medicine, Copenhagen, Denmark
JOINT1159
Introduction: The bone resorption marker C-terminal telopeptide of Type I collagen (β-CTX-I), measured in plasma or serum is used to assess bone metabolism and therapeutic response in bone disorders. Studies have shown poor agreement in results between commercial assays for β-CTX-I and harmonization of assays has been proposed by the IFCC-IOF Committee for Bone Metabolism to achieve widely and interchangeably use of the assays.
Objective: To evaluate the performance of a new Beta CrossLaps® (CTX-I) (IDS-NEW) assay from Immunodiagnostic Systems (IDS) and to compare it with the existing IDS-iSYS CTX-I (CrossLaps®) assay (IDS-OLD) and the Roche Elecsys® β-CrossLaps/serum assay (ELECSYS).
Methods: Patient EDTA plasma samples were obtained. Precision of the IDS-NEW assay was assessed by measuring two patient pools (one around the geometric mean for premenopausal women and one at a higher level). Each level was run on every weekday in a period of two weeks, n = 30. Both the IDS-ISYS (iSYS) and IDS-i10 (i10) platforms were used. Correlation between the IDS-NEW assay, the current IDS-OLD assay and the ELECSYS assay were evaluated by measuring patient samples in parallel on the different assays.
Results: Precision of the IDS-NEW assay is shown in table 1. Parallel analysis of patient samples (n =68) using the IDS-NEW assay on the iSYS and i10 system showed a high correlation (R2 = 0.994, P< 0.0001) with a negligible bias of 0.5 ng/l (P = 0.9177). Method comparison between the IDS-NEW and IDS-OLD assays (n =93) showed a high correlation (R2 = 0.983, P< 0.0001) with a non-significant bias of 28 ng/l (P = 0.1203). However, a complex systematic bias with the IDS-NEW assay giving higher values at low concentrations and lower values at high concentrations compared to the IDS-OLD was seen. Finally, parallel analysis of patient samples (n =40) on the IDS-NEW assay and the Elecsys assay showed a high correlation (0.9841, P< 0.0001) with a mean bias of 14 ng/l (P = 0.2523). A possible lower correlation between the assays was observed at concentrations below 200 ng/l. New reference intervals for children will be presented.
| Level | CV (%) | SD |
| Medium (340 ng/l) | 4.6 | 15.5 |
| High (839 ng/l) | 3.9 | 33.0 |
Conclusions: - There is a high correlation between the IDS-NEW and the ELECSYS assay.- Steps towards harmonization of the IDS-NEW assay with the ELECSYS assay have now been taken. However, whether interchangeable use of the two assays for monitoring individual patients over time is yet to be determined
Volume 110
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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