lupus anticoagulant

(also known as lupus antibody, LA, or lupus inhibitors) is a medical phenomenon where autoantibodies bind to phospholipids and proteins associated with the cell membrane. Since interactions between the cell membrane and clotting factors are necessary for proper functioning of the coagulation cascade, the lupus anticoagulant can interfere with blood clotting as well as in-vitro tests of clotting function. Paradoxically, lupus anticoagulants are also risk factors for thrombosis.

Conceptually, lupus anticoagulants overlap with the antiphospholipid antibody syndrome. Lupus anticoagulants can be understood as the tendency of antiphospholipid antibodies to prolong the clotting times, especially in phospholipid rich clotting testing such as the dilute Russell's viper venom time.

Often, the lupus anticoagulant is diagnosed on asymptomatic patients by a routine blood testing prior to surgery. Patients with a lupus anticoagulant are prone to thrombosis, excess bleeding, and habitual abortion (repeated miscarriages).

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Antiphospholipid syndrome (APS or APLS) or antiphospholipid antibody syndrome is a disorder of coagulation that causes blood clots (thrombosis) in both arteries and veins as well as pregnancy-related complications such as miscarriage, stillbirth, preterm delivery, or severe preeclampsia. The syndrome occurs due to the autoimmune production of antibodies against phospholipid (aPL), a cell membrane substance. In particular, the disease is characterised by antibodies against cardiolipin (anti-cardiolipin antibodies) and β2 glycoprotein I.

The term "primary antiphospholipid syndrome" is used when APS occurs in the absence of any other related disease. APS is commonly seen in conjunction with other autoimmune diseases; the term "secondary antiphospholipid syndrome" is used when APS coexists with other diseases such as systemic lupus erythematosus (SLE). In rare cases, APS leads to rapid organ failure due to generalised thrombosis and a high risk of death; this is termed "catastrophic antiphospholipid syndrome" (CAPS).

Antiphospholipid syndrome is sometimes referred to as Hughes syndrome after the rheumatologist Dr. Graham R.V. Hughes (St. Thomas' Hospital, London, UK) who worked at the Louise Coote Lupus Unit at St Thomas' Hospital in London.

Often, this disease is treated by giving aspirin to inhibit platelet activation, and/or warfarin as an anticoagulant. The goal of the prophylactic treatment is to maintain the patient's INR between 3.0 - 4.0.[5] It is not usually done in patients who have not had any thrombotic symptoms. During pregnancy, low molecular weight heparin and low-dose aspirin are used instead of warfarin because of warfarin's teratogenicity. Women with recurrent miscarriage are often advised to take aspirin and to start low molecular weight heparin treatment after missing a menstrual cycle. In refractory cases plasmapheresis may be used.