Lupus anticoagulants are a heterogeneous family of immunoglobulins (antibodies) seen in antiphospholipid syndrome that may develop spontaneously or as a consequence of several different autoimmune disorders. Lupus anticoagulant antibodies bind to phospholipids, which are necessary for normal blood clotting, and interfere with the normal clotting process.
Role in Autoimmune Disease
Despite their name, lupus anticoagulants and antiphospholipid syndrome can develop in many conditions besides systemic lupus erythematosus (SLE), including Crohn’s disease, ulcerative colitis, and autoimmune thyroid disorders. Certain drugs, including phenothiazines and ACE inhibitors may precipitate the development of lupus anticoagulants. Lupus anticoagulants are seen in about 25-35 percent of patients with SLE.
Lupus anticoagulant is seen in 2-4 percent of the population. Persistently positive tests for lupus anticoagulant are risk factors for the occurrence and recurrence of venous and arterial blood clots and/or pregnancy morbidity and miscarriage.
Lupus anticoagulants cause prolonged clotting in certain clotting tests, including the prothrombin time (PT) test. Patients with lupus anticoagulant may bruise easily after injury and show other signs of abnormal blood clotting such a, migraine headaches, deep vein thromoses (clots), renal vein thromboses, and stroke. Rarely, patients may show signs of bleeding including bleeding gums, nose bleeds, abnormal vaginal bleeding, bloody urine and rash.
There is no one specific test used to diagnose lupus anticoagulants. Patients with lupus anticoagulants may have an elevated PT test, and elevated activated partial thromboplastin test (PTT), and elevated DVVT (dilute Russell venom viper test), and elevated kaolin clotting time (KCT), abnormal levels of Protein C or Protein S, or antiphospholipid (anticardiolipin) antibodies.
Mixing tests are used to tell if elevations in PT or PTT are due to antibodies or deficiencies in specific clotting factors.
Patients with lupus anticoagulants are treated with anticoagulants such as heparin to reduce their risk of developing blood clots.