Validation of 4% albumin as a diluent in the Bethesda Assay for FVIII inhibitors.

Introduction: External quality assurance programs show the Nijmegen Bethesda Assay for FVIII inhibitors improves test specificity compared to the Classic Bethesda Assay but its uptake has been slow possibly due to the cost of using FVIII deficient plasma as diluent. This study was conducted to determine if modifying the Nijmegen Bethesda assay by replacement of FVIII deficient plasma with 4% as a diluent would be suitable for for measuring FVIII inhibitors.

Materials And Methods: The titres of 59 samples from 35 patients with FVIII inhibitors were determined in parallel tests by the Nijmegen Bethesda Assay and and the modified Nijmegen assay.

Laboratory identification of factor inhibitors: the perspective of a large tertiary hemophilia center.

Coagulation factor inhibitors are antibodies that bind and neutralize specific procoagulant plasma proteins. The identification of coagulation factor inhibitors by the hemostasis laboratory requires a careful and systematic approach that excludes other possible causes of prolonged screening tests such as the activated partial thromboplastin time and prothrombin time. Once the laboratory is confident that a specific coagulation factor inhibitor is present in a sample, its strength or titer must be measured.