title: Comparison of three methods for measuring factor VIII levels in plasma.
abstract: We compared 1-stage clot-based, chromogenic, and immunoassay methods for measuring factor VIII in plasma with a focus on the measurement of elevated levels of factor VIII. The chromogenic assay showed the best interassay imprecision for factor VIII levels near 150 IU/dL. The best correlation was between the 1-stage clot-based and chromogenic factor VIII assays (r2 = 0.934), and the lowest correlation was between the 1-stage clot-based and antigenic factor VIII assays (r2 = 0.821). The presence of heparin, low-molecular-weight heparin, lepirudin, or lupus inhibitors in the sample resulted in major interference in the 1-stage clot-based assay but not the chromogenic or antigenic factor VIII assays. Overall, the chromogenic factor VIII activity assay was the optimal method, showing good precision, the best overall correlation with other assays, and no interference from heparin, low-molecular-weight heparin, lepirudin, or lupus inhibitors.
authors.affiliation: Dept of Laboratory Medicine, Box 357110, University of Washington, Seattle, WA 98195, USA.
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Chandler
authors.forename: Chris
authors.initials: C
authors.lastname: Ferrell
authors.forename: Joo
authors.initials: J
authors.lastname: Lee
authors.forename: Theingi
authors.initials: T
authors.lastname: Tun
authors.forename: Hien
authors.initials: H
authors.lastname: Kha
mesh_terms: D001777:Blood Coagulation / Q000502:physiology; D001780:Blood Coagulation Tests / Q000379:methods*; D002863:Chromogenic Compounds / Q000032:analysis; D005167:Factor VII / Q000032:analysis* / Q000276:immunology; D006801:Humans; D007118:Immunoassay; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results
chemical_list: D002863:Chromogenic Compounds; D011933:Reagent Kits, Diagnostic; D005167:Factor VII