Lupus anticoagulant

A type of antibody associated with increased risk of thrombosis

Lupus anticoagulant
Synonyms	Lupus antibody, LA, LAC, lupus inhibitors
Specialty	Hematology, Immunology
Symptoms	Thrombosis, recurrent miscarriage, prolonged activated partial thromboplastin time (aPTT)
Complications	Deep vein thrombosis, pulmonary embolism, stroke, pregnancy loss
Usual onset	Variable (often detected during clotting evaluation)
Duration	Can be transient or persistent
Types	Associated with Antiphospholipid syndrome
Causes	Autoantibodies targeting phospholipid-binding proteins (e.g., β2-glycoprotein I)
Risk factors	Systemic lupus erythematosus (SLE), HIV, hepatitis C, certain medications
Diagnosis	Positive testing on at least two occasions, 12 weeks apart; includes dRVVT, aPTT, and LA-sensitive assays
Differential diagnosis	Other causes of thrombosis, protein C deficiency, antithrombin III deficiency, factor V Leiden
Prevention	Risk management for thrombosis in high-risk individuals
Treatment	Anticoagulation therapy
Medication	Warfarin, heparin, low-molecular-weight heparin
Prognosis	Variable; higher risk of complications with antiphospholipid syndrome
Frequency	Present in ~1–5% of general population; higher in autoimmune diseases
Deaths	Related to thrombotic complications if untreated

Lupus anticoagulant is an autoantibody associated with an increased risk of thrombosis, or blood clot formation. Despite its name, lupus anticoagulant is not related to lupus erythematosus and does not cause bleeding. Instead, it interferes with the normal clotting process, leading to a paradoxical increase in clotting risk.

Pathophysiology

Lupus anticoagulant is a type of antiphospholipid antibody that targets phospholipids and phospholipid-binding proteins in the cell membrane. These antibodies interfere with the coagulation cascade, particularly affecting the prothrombin and activated partial thromboplastin time (aPTT) tests, which are used to assess blood clotting. The presence of lupus anticoagulant prolongs these clotting times in vitro, but in vivo, it predisposes individuals to thrombosis.

Clinical Significance

Lupus anticoagulant is a key component of the antiphospholipid syndrome (APS), a disorder characterized by recurrent venous or arterial thrombosis and pregnancy complications such as recurrent miscarriage. Patients with lupus anticoagulant may experience deep vein thrombosis, pulmonary embolism, stroke, or other thrombotic events.

Diagnosis

The diagnosis of lupus anticoagulant involves a series of blood tests. Initial screening includes the activated partial thromboplastin time (aPTT) and the dilute Russell's viper venom time (dRVVT). If these tests are prolonged, further confirmatory tests are performed, such as mixing studies and phospholipid neutralization procedures, to confirm the presence of lupus anticoagulant.

Management

Management of patients with lupus anticoagulant focuses on reducing the risk of thrombosis. This often involves the use of anticoagulant medications such as warfarin or heparin. In patients with antiphospholipid syndrome, long-term anticoagulation may be necessary. During pregnancy, low-dose aspirin and heparin are commonly used to prevent complications.

Related pages

• Antiphospholipid syndrome
• Thrombosis
• Autoantibody
• Coagulation