Plasma-activated factor VII level in patients positive for lupus anticoagulant

We examined plasma levels of activated factor VII (F VIla) in 50 patients positive for lupus anticoagulant (LA), in 83 patients negative for LA, and in 10 healthy volunteers as controls. Plasma F VIIa was present in healthy volunteers; its level was significantly increased, compared to the level in the controls, in patients with thrombosis, collagen diseases, and disseminated intravascular coagulation (DIC), suggesting that it reflected a thrombotic state. Plasma F VIIa was correlated with thrombin-antithrombin complex (TAT) in patients negative for LA but showed no such correlation in those positive for LA. Plasma F VIIa was negatively correlated with activated partial thromboplastin time (APTT) in patients positive for LA, but not in those negative for LA, suggesting that LA could inhibit the F VIIa assay system. Plasma F VIIa level was significantly increased in patients with thrombotic diseases; however, in patients positive for LA, it is possible that increased plasma F VIIa level may not be correlated with thrombogenicity.