Table 2.

International Society on Thrombosis and Hemostasis criteria for the laboratory identification of lupus anticoagulant⁹.

Positive screening test (phospholipid-dependent coagulation assay) Two or more screening tests recommended: Dilute Russell’s viper venom time (DRVVT) and a sensitive aPTT (low phospholipids with silica as activator)

Evidence of inhibition in mixing studies (exclude factor deficiency) 1:1 mixing of patient plasma with normal plasma does not correct the prolonged clotting time LA cannot be conclusively identified if thrombin time is prolonged

Evidence that inhibition is phospholipid dependent Confirmatory test(s) performed by performing tests in which increased phospholipid corrects or reduces the prolonged clotting time Examples: DRVVT confirm, hexagonal phase phospholipid, platelet neutralization test, others

Exclusion of coagulation inhibitors Heparin Direct thrombin or factor Xa inhibitors (DOAC) Coagulation factor inhibitors (e.g. factor VIII inhibitor)