Cite this page: Parsons J. Factor VIII inhibitor assay / Bethesda assay. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/coagulationfactorVIIIinhibitorassay.html. Accessed June 7th, 2020.
Definition / general
- Prepare serial dilutions of patient plasma in citrated saline from 1 : 1 to 1 : 160 (or higher)
- Mix each dilution with an equal volume of normal plasma containing a normal amount of coagulation factors, incubate for 2 hours, then perform factor VIII assay
- Titer of inhibitor is dilution that inhibits 50% of factor VIII in assay
- Can use porcine Factor VIII to assess cross-reactivity and assist in therapeutic decisions