• A B Connell, N Jenkins, M Black, J A Pasco, M A Kotowicz, and H-G Schneider.
• Clinical Biochemistry Unit, Alfred Pathology Service, Melbourne,Victoria, Australia.
• Pathology. 2011 Jun 1; 43 (4): 368-71.

BackgroundVitamin D deficiency is common. Recently Roche Diagnostics removed their Elecsys Vitamin D3 (25OH) electrochemiluminescence immunoassay (ECLIA) from use, citing deteriorating traceability to the reference method (liquid chromatography tandem mass spectrometry; LCMSMS). We investigated the performance of the Roche assay (2 assay formulations) against an LCMSMS method and the widely used DiaSorin radioimmunoassay (RIA) method.MethodsTwo sets of samples from separate populations were assayed for vitamin D. The first set was assayed using three different methods: RIA (DiaSorin) in 2004, polyclonal ECLIA (Roche) in early 2009 and LCMSMS in early 2010. The second set was assayed using polyclonal and monoclonal ECLIA (Roche) and LCMSMS in mid-2010.ResultsThe correlation of the polyclonal ECLIA with the RIA was poor (ECLIA = 0.45 × RIA + 19, r(2) = 0.59, n = 773). LCMSMS results correlated with RIA (RIA = 0.86 × LCMSMS + 4, r(2) = 0.69, n = 49) better than with polyclonal ECLIA (polyclonal ECLIA = 0.55 × LCMSMS + 6, r(2) = 0.62, n = 55) despite a storage interval of 6 years.In recently collected samples monoclonal and polyclonal immunoassays gave similar results (monoclonal ECLIA = 0.93 polyclonal ECLIA -3, r(2) = 0.60, n = 153). The correlation between monoclonal Roche ECLIA and LCMSMS in these samples was very poor (monoclonal ECLIA = 0.31 × LCMSMS + 23, r(2) = 0.27).ConclusionsAt the time of its removal from the market, the Roche Elecsys Vitamin D3 (25OH) assay showed unacceptable performance, underestimating vitamin D levels. It seems that this bias preceded the introduction of the monoclonal assay. The worldwide distribution of the assay and the duration of this bias likely led to a significant number of patients starting supplementation unnecessarily.

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