Circulating lupus anticoagulants are autoantibodies produced by a person’s immune system against his or her own phospholipids. These phospholipids are found on the surface of platelets and intervene in the activation of several factors responsible for blood clotting (clot formation). Lupus anticoagulants are often responsible for the abnormal formation of clots in veins (phlebitis) and arteries (arterial thromboses), and they increase the risk of heart attack, pulmonary embolism and stroke. They are also involved in repeated miscarriages occurring in the second or third trimester of pregnancy. Screening for circulating anticoagulants takes place in multiple stages, some of which use Russell’s viper venom (RVV), diluted activated partial thromboplastin time (PTT-LA) or phospholipid extracts (Staclot).
Test results are interpreted by a hematologist (see interpretation) and indicate whether or not a lupus anticoagulant is likely to be present as well as certain limitations of the test. Circulating lupus anticoagulants are found not only in systemic lupus erythematosus, but also in other autoimmune diseases, infections, inflammations, cancers, and in some patients treated with procainamide, phenothiazine, etc.