title: Conventional rapid latex agglutination in estimation of von Willebrand factor: method revisited and potential clinical applications.
abstract: Measurement of von Willebrand factor antigen (VWF : Ag) levels is usually performed in a specialised laboratory which limits its application in routine clinical practice. So far, no commercial rapid test kit is available for VWF : Ag estimation. This paper discusses the technical aspect of latex agglutination method which was established to suit the purpose of estimating von Willebrand factor (VWF) levels in the plasma sample. The latex agglutination test can be performed qualitatively and semiquantitatively. Reproducibility, stability, linearity, limit of detection, interference, and method comparison studies were conducted to evaluate the performance of this test. Semiquantitative latex agglutination test was strongly correlated with the reference immunoturbidimetric assay (Spearman's rho = 0.946, P < 0.001, n = 132). A substantial agreement (κ = 0.77) was found between qualitative latex agglutination test and the reference assay. Using the scoring system for the rapid latex test, no agglutination is with 0% VWF : Ag (control negative), 1+ reaction is equivalent to <20% VWF : Ag, and 4+ reaction indicates >150% VWF : Ag (when comparing with immunoturbidimetric assay). The findings from evaluation studies suggest that latex agglutination method is suitable to be used as a rapid test kit for the estimation of VWF : Ag levels in various clinical conditions associated with high levels and low levels of VWF : Ag.
authors.affiliation: Departments of Haematology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia.
authors.forename: Marianor
authors.identifier: 0000-0002-2214-5839
authors.initials: M
authors.lastname: Mahat
authors.affiliation: Departments of Haematology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia.
authors.forename: Wan Zaidah
authors.identifier: 0000-0001-7113-475X
authors.initials: WZ
authors.lastname: Abdullah
authors.affiliation: Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia.
authors.forename: Che Maraina Che
authors.initials: CM
authors.lastname: Hussin
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D007118:Immunoassay; D007841:Latex Fixation Tests / Q000379:methods*; D009391:Nephelometry and Turbidimetry / Q000379:methods; D012015:Reference Standards; D015203:Reproducibility of Results; D014842:von Willebrand Diseases / Q000175:diagnosis*; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor