title: von Willebrand factor ristocetin cofactor (VWF:RCo) assay: implementation on an automated coagulometer (ACL).
abstract: BACKGROUND
  VWF:RCo assay is the standard and widely used laboratory test for von Willebrand disease (VWD) diagnosis. It is hampered by high intra- and inter-assay imprecision and is time consuming. Automation may improve the assay performance and allow its routine application.
  
  
  OBJECTIVE
  Automation of VWF:RCo on the ACL 7000 coagulometer (Instrumentation Laboratory, Milan, Italy) and its evaluation in VWD diagnosis.
  
  
  METHODS
  Method performance determination: precision, detection limit (DL), interferences, dose-response curve. Method comparison: analysis of 105 plasma samples from normal subjects (50), VWD type 1 (24), VWD type 2 (24) and VWD type 3 (7) with ACL VWF:RCo and comparison with the reference aggregometric (AGM) method.
  
  
  RESULTS
  ACL VWF:RCo: CVs around 10% vs. 19% of AGM method; DL: 0.08 U mL(-1); potential interferences from bilirubin, triglycerides and hemoglobin, avoided by suitable plasma dilution; high correlation with AGM VWF:RCo (Deming regression Y =-0.0277 + 1.0519X) either in normal or VWD plasmas. In VWD types 1 and 2, the VWF:RCo/VWF:Ag ratios are >0.6 or <0.6, respectively, when calculated with both AGM and ACL VWF:RCo values.
  
  
  CONCLUSIONS
  The automated VWF:RCo on the ACL 7000 coagulometer shows precision improvement and high correlation with the reference AGM method. The test allows the diagnosis of both quantitative (VWD types 1 and 3) and qualitative (VWD type 2) forms of the disease. These results and the assay feasibility make it a suitable and reliable test for the routine diagnosis of VWD.
authors.affiliation: Department of Hematology, Thrombosis and Hemostasis Unit, Ospedale Niguarda Ca' Granda, Milan, Italy. rosaria.redaelli@ospedaleniguardia.it
authors.forename: R
authors.initials: R
authors.lastname: Redaelli
authors.forename: A R
authors.initials: AR
authors.lastname: Corno
authors.forename: L
authors.initials: L
authors.lastname: Borroni
authors.forename: G
authors.initials: G
authors.lastname: Mostarda
authors.forename: M
authors.initials: M
authors.lastname: Nichelatti
authors.forename: E
authors.initials: E
authors.lastname: Morra
authors.forename: F
authors.initials: F
authors.lastname: Baudo
mesh_terms: D001331:Automation; D001663:Bilirubin; D001780:Blood Coagulation Tests / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D006454:Hemoglobins; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014280:Triglycerides; D014842:von Willebrand Diseases / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000032:analysis*
chemical_list: D006454:Hemoglobins; D014280:Triglycerides; D014841:von Willebrand Factor; D001663:Bilirubin