title: The new Roche Vitamin D Total assay: fit for its purpose?
abstract: BACKGROUND
  Measurement of serum 25-hydroxyvitamin D [25(OH)D] is used to assess vitamin D status. We evaluated the analytical performance of a new automated assay, Elecsys Vitamin D Total (Roche Diagnostics, Mannheim, Germany), based on competitive protein binding.
  
  
  METHODS
  The Elecsys assay was tested for imprecision, linearity and functional sensitivity at three test-sites and compared to a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, a high-performance liquid chromatography (HPLC) method and the Liaison 25(OH) Vitamin D Total immunoassay (Diasorin).
  
  
  RESULTS
  Imprecision testing with human serum specimens showed within-run CVs of ≤6% and between-run CVs of ≤8%. The assay was linear from 33 up to at least 111 nmol/L and showed equivalent 25(OH)D levels for matched serum and heparinized plasma samples. The assay correlated reasonable to well with LC-MS/MS (r=0.93; y=1.07x-5.04 nmol/L), HPLC (r=0.91, y=0.90x+3.03 nmol/L) and the Liaison assay (r=0.86, y=1.19x+2.80 nmol/L). Some of the samples showed large between-method differences.
  
  
  CONCLUSIONS
  The new Elecsys assay fulfilled present analytical performance requirements and showed close agreement to other well-established methods for 25(OH)D analysis, making it fit for routine assessment of vitamin D status.
authors.affiliation: Laboratory for Clinical Chemistry, Máxima Medical Center, Veldhoven, The Netherlands. j.emmen@mmc.nl
authors.forename: Judith M A
authors.initials: JM
authors.lastname: Emmen
authors.forename: Jos P M
authors.initials: JP
authors.lastname: Wielders
authors.forename: Arjen-Kars
authors.initials: AK
authors.lastname: Boer
authors.forename: Johannes M W
authors.initials: JM
authors.lastname: van den Ouweland
authors.forename: Huib L
authors.initials: HL
authors.lastname: Vader
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards; D006801:Humans; D012015:Reference Standards; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D