Validation of an automated latex particle-enhanced immunoturbidimetric von Willebrand factor activity assay

D. Chen, J. I. Tange, B. J. Meyers, R. K. Pruthi, W. L. Nichols, J. A. Heit

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Background:Laboratory diagnosis of von Willebrand disease (VWD) requires accurate measurement of plasma von Willebrand factor (VWF) activity. Objectives:To evaluate laboratory characteristics, diagnostic accuracy and testing utilities of an automated latex particle-enhanced immunoturbidimetric VWF assay (VWF:Lx) based on a monoclonal antibody recognizing the VWF-platelet glycoprotein (GP) Ib binding domain. Methods:Laboratory characteristics including lower detection limit, linearity, precision, sample stability, and method comparison between VWF:Lx and VWF ristocetin cofactor activity by platelet aggregometry (VWF:RCo) were examined. To assess VWF:Lx diagnostic accuracy, 492 patient plasma samples, including 40 previously characterized VWD patient samples, were tested for VWF antigen (VWF:Ag) and VWF:RCo by either aggregometry or flow cytometry, and VWF:Lx with supplemental VWF multimer analysis when indicated. Based on results of VWF:Ag, VWF:RCo and VWF multimer analysis, and available clinical information, samples were categorized as: normal; VWD types 1, 2A/B, 2M, or severe 1 vs. 2M; or acquired VWF abnormalities (AVWA) due to subtle loss of highest molecular weight multimers. Results:VWF:Lx had excellent laboratory characteristics and linear correlation with VWF:RCo (R 2=0.93). VWF:Lx accurately classified virtually all normal and VWD patient samples. Compared with VWF:RCo, VWF:Lx had superior sensitivity and specificity for distinguishing severe type 1 vs. 2M VWD and identifying AVWA. A proposed screening panel comprising VWF:Ag and VWF:Lx had 100% and 83% sensitivity for detecting VWD and AVWA, respectively. Conclusions:VWF:Lx has excellent laboratory characteristics and diagnostic accuracy compared with VWF:RCo, and can be used as part of an initial VWD screening panel and as a supplementary test.

Original languageEnglish (US)
Pages (from-to)1993-2002
Number of pages10
JournalJournal of Thrombosis and Haemostasis
Issue number10
StatePublished - Oct 2011


  • Latex immunoassay
  • Ristocetin cofactor activity
  • Von Willebrand disease
  • Von Willebrand factor activity

ASJC Scopus subject areas

  • Hematology


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