Analytical evaluation of the new Abbott Architect 25-OH vitamin D assay Etienne Cavalier a, ⁎ , 1 , Agnes Carlisi a , Anne-Catherine Bekaert a , Olivier Rousselle a , Jean-Paul Chapelle a , Jean-Claude Souberbielle b, 1 a Department of Clinical Chemistry, University of Liege, CHU Sart-Tilman, Liège, Belgium b Laboratoire d'Explorations fonctionnelles, Hôpital Necker-Enfants malades, Paris, France abstract article info Article history: Received 16 September 2011 Received in revised form 20 January 2012 Accepted 21 January 2012 Available online 1 February 2012 Keywords: Vitamin D Analytical validation Immunoassay Objectives: Validation of the Architect 25-OH vitamin D assay. Design and methods: Determination of repeatability, reproducibility, accuracy profile and 25(OH)-vitamin D2 recovery on native samples. Comparison with DiaSorin Liaison and RIA. Results and conclusion: Coefficients of variation: b 6% (13.6 ng/mL) and 2.2% (78.1 ng/mL). Functional sen- sitivity: 5 ng/mL. Accuracy profile shows that the method is validated between 13.6 and 78.1 ng/mL. Recovery of 25(OH)D2: 75,8%( 95% CI: 61.9–89.7%). Good correlation with DiaSorin RIA and Liaison b 50 ng/mL; above this threshold a systematic positive bias was observed. © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. Introduction Vitamin D (VTD) (which is actually not a vitamin but a prohor- mone) can be found in two forms: the first one, vitamin D3 (cho- lecalciferol) is the molecule synthesized in the skin and which is present in some foods (mainly fat fish from cold seas). The second, vitamin D2 (ergocalciferol), is the vitamin D of the plants. Vitamin D2 or D3 can also be found in many pharmacological supplements. To be active, VTD must be hydroxylated twice to produce the most biologically active form of VTD, 1,25(OH) 2 -vitamin D. However, it is clear now that serum 25(OH)D is the correct functional indica- tor of vitamin D status [1]. In the last decade, the increasing number of publications on VTD has fuelled the global demand for 25-OH D testing [2]. Clinical laboratories have thus been put under pressure to seek automated reliable platforms for 25(OH)D analysis to keep up with the demanded volume. Recently, Abbott Diagnostics (Wiesbaden, Germany) have launched a kit for the 25(OH)D determination on the Architect platform. The aim of this multicentre study was to validate this new kit on the Architect i1000 SR platform. Materials and methods Analytical method The Architect 25-OH Vitamin D assay is a delayed one-step immu- noassay that uses a polyclonal anti-vitamin D antibody from sheep or- igin coated on paramagnetic particles and a biotinylated vitamin D anti-biotin acridinium labelled conjugated complex. Statistical softwares We used the Medcalc (Mariakerke, Belgium) and the e-noval (Arlenda, Liège, Belgium) softwares for the statistical evaluation of the results. Samples We only used serum samples for 25(OH)D determination. All the samples were treated according to our preanalytical procedure: after sampling, they were spun at + 4 °C at 3500 G, aliquoted and kept frozen at -20 °C until determination, as it has been shown that 25(OH)D was particularly stable [3]. As vitamin D2 is not present in Belgium, we fortified volunteer members of our staff with 600.000 IU of a vitamin D2 pharmacological preparation imported from France (Sterogyl 15 “A”, Desma Pharma, La Varenne Saint- Hilaire, France). Samples from these volunteers were drawn after 7 days. Clinical Biochemistry 45 (2012) 505–508 ⁎ Corresponding author at: Department of Clinical Chemistry, Centre Hospitalier Universitaire de Liège, Domaine du Sart-Tilman, B-4000 Liège, Belgium. Fax: + 32 43667691. E-mail address: Etienne.cavalier@chu.ulg.ac.be (E. Cavalier). 1 EC and JCS have received different lecture fees from Abbott, DiaSorin, Roche and IDS. 0009-9120/$ – see front matter © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.clinbiochem.2012.01.021 Contents lists available at SciVerse ScienceDirect Clinical Biochemistry journal homepage: www.elsevier.com/locate/clinbiochem