Abstract
We examined activated partial thromboplastin time, kaolin clotting time, mixing with normal plasma in kaolin clotting time, dilute Russell's viper venom time, dilute Rus sell's viper venom time at high lipid concentrations, anti phospholipid antibodies, and anti-cardiolipin-β2-glycoprotein I complex antibody in 135 patients with prolongation of acti vated partial thromboplastin time and diagnosed 86 patients positive for lupus anticoagulant. The sensitivity of activated partial thromboplastin time and dilute Russell's viper venom time/dilute Russell's viper venom time-high lipid concentra tions ratio for lupus anticoagulant were markedly high, but the specificity of activated partial thromboplastin time for lupus anticoagulant was not markedly high. The specificity, but not the sensitivity, of kaolin clotting time-mixing with normal plasma in kaolin clotting time was markedly high. In summary, dilute Russell's viper venom time to dilute Russell's viper venom time-high lipid concentrations ratio gave high sensitiv ity as well as specificity, being the only assay to confirm this. Of the patients positive for lupus anticoagulant, 25% were posi tive for anti-phospholipid antibodies and 17% were positive for anti-cardiolipin-β2-glycoprotein I complex antibody. Of the lu pus anticoagulant-positive patients with thrombosis, 45% were positive for anti-phospholipid antibodies, 35% were positive for anti-cardiolipin-β2-glycoprotein I complex antibody, 60% were positive for both anti-phospholipid antibodies and anti cardiolipin-β2-glycoprotein I complex antibody, and only 17% were negative for anti-phospholipid antibodies and anti cardiolipin-β2-glycoprotein I complex antibody. These find ings suggest that lupus anticoagulant can be diagnosed by di lute Russell's viper venom time/dilute Russell's viper venom time-high lipid concentrations ratio, and that thrombosis in lupus anticoagulant-positive may be predictable from both anti-phospholipid antibodies and anti-cardiolipin-β2- glycoprotein I complex antibody. Plasma tissue type plasmin ogen activator level in lupus anticoagulant patients was signifi cantly increased, and plasma tissue type plasminogen activator and fibrin-D-dimer levels in lupus anticoagulant-positive pa tients with thrombosis were significantly higher than in those without thrombosis, suggesting that the diagnosis of thrombo sis by hemostatic markers might be important in lupus antico agulant.