Open AccessAutomated Competitive Protein‐Binding Assay for Total 25‐OH Vitamin D, Multicenter Evaluation and Practical Performance
Author(s) -
Wielders Jos PM,
Carter Graeme F.,
Eberl Heike,
Morris Gary,
Jürgen Roth Heinz,
Vogl Christian
Publication year - 2015
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.21793
Subject(s) - repeatability , vitamin d and neurology , vitamin d binding protein , chromatography , immunoassay , chemistry , high performance liquid chromatography , external quality assessment , medicine , antibody , immunology , pathology
Background The Roche Elecsys Vitamin D Total competitive protein‐binding assay uses recombinant vitamin D binding protein for measuring 25‐hydroxyvitamin D (25‐OHD), which is different from commonly used antibody assays. Methods The assay, standardized against LC‐MS/MS, was tested at four sites. Evaluation included precision; between‐laboratory variability; functional sensitivity; correlation to LC‐MS/MS, HPLC, and immunoassays; as well as robustness, traceability, and EQAS performance. Results Precision testing showed within‐run coefficient of variations (CVs) of ≤7%, within‐laboratory CVs of <9.5%, between‐laboratory precision CVs of ≤10.1%, and a functional sensitivity below 9.8 nmol/l (at CV 12.9%). The assay showed equivalent 25‐OHD levels for matched serum and plasma samples, good reagent lot‐to‐lot consistency in pooled sera over time, and good agreement with HPLC (relative bias −8.8%). Comparison with LC‐MS/MS methods yielded relative biases of −15.4, −13.5, −10.2, and 3.2%. Comparison against immunoassays showed a relative bias of 14.5% (DiaSorin Liaison) and −58.2% (IDS‐iSYS). The overall mean results in 2 years DEQAS was 102% of the ALTM. In a certified reference patient panel, the average bias was <4% for the sum of 25‐OHD2 and 25‐OHD3. Conclusion The Elecsys Vitamin D Total assay demonstrated good overall performance and is, according to present standards, very suitable for automated measurement of 25‐OHD.