title: Analysis of the 2010-2012 results of the multicenter external proficiency study for 25-hydroxyvitamin D.
abstract: BACKGROUND
  Results collected from the 2010-2012 cycles of the 'Immunocheck' external quality assessment scheme for 25-hydroxyvitamin D, conducted by QualiMedLab CNR (Italy) and ProBioQual (France; 250 among Italian and French laboratories) are presented in this article.
  
  
  METHODS
  Details of how QualiMedLab operates can be found in QualiMedLab website.
  
  
  RESULTS
  Interlaboratory imprecision was 19 (2010), 15 (2011) and 13% (2012). The LIAISON(®) analyzer (DiaSorin, Italy) was the most utilized, followed by Roche (UK), ImmunoDiagnostic Systems methods (UK), ARCHITECT (Abbott, IL, USA), radioimmunoassay (DiaSorin) and others. The within-method variability between laboratories (percentage coefficient of variation) were 15, 12.7 versus 9.8% for LIAISON, 27.8, 16.5 versus 11.7% for Roche, 15, 12 versus 17% for ImmunoDiagnostic Systems and 17.4, 18.6 versus 17.5% for radioimmunoassay in the 2010, 2011 versus 2012 cycles, and 15 versus 8.9% for ARCHITECT in the 2011 versus 2012, respectively.
  
  
  CONCLUSIONS
  Significant differences in specific samples and discrepancies between laboratories and methods still exist, making the actuation of appropriate external quality assessment schemes mandatory.
authors.affiliation: Fondazione G Monasterio CNR-Regione Toscana, Via Moruzzi 1, I-56124, Pisa, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Bianchi
authors.forename: Stefania
authors.initials: S
authors.lastname: Giovannini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Zucchelli
authors.forename: Aldo
authors.initials: A
authors.lastname: Clerico
authors.forename: Martina
authors.initials: M
authors.lastname: Pierini
authors.forename: Rudina
authors.initials: R
authors.lastname: Ndreu
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vannucci
authors.forename: Debora
authors.initials: D
authors.lastname: Battaglia
authors.forename: Cristina
authors.initials: C
authors.lastname: Vassalle
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D006801:Humans; D015337:Multicenter Studies as Topic / Q000379:methods*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D