Cite this page: Parsons JC. Factor V Leiden assay. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/coagulationfactorVleiden.html. Accessed January 12th, 2025.
Definition / general
- Dilute patient plasma 1 : 5 with factor V deficient plasma (dilutes the effect of other factor deficiencies or elevations) and add polybrene (neutralizes unfractionated heparin or low molecular weight heparin)
- If lupus anticoagulant is present, must perform DNA based test for Factor V Leiden (or perhaps 1 : 40 dilution of plasma or add phospholipids to neutralize lupus anticoagulant)
- Calculate ratio of PTT with versus without exogenous activated protein C; normal is 2.0 or more, factor V Leiden usually < 2.0 (sensitivity and specificity approach 100%, because these patients activated factor V resists activated protein C degradation)
- Prothrombin - based factor V assay with factor V deficient plasma (no interference from lupus anticoagulant)
- Modified Russell viper venom time test (high phospholipids neutralizes lupus anticoagulant)
- Factor Xa - based assay with factor V deficient plasma
- DNA based tests such as PCR (using whole blood, not plasma)
Additional references