Antiphospholipid syndrome is an autoimmune disorder caused by antiphospholipid antibodies. These antibodies target the proteins that bind to the phospholipids on the cell surface, causing inflammation and increasing the risk of thrombosis (blood clots). It can occur in isolation or associated with another autoimmune condition, particularly systemic lupus erythematosus.
Antibodies
The specific antiphospholipid antibodies are:
- Lupus anticoagulant
- Anticardiolipin antibodies
- Anti-beta-2 glycoprotein I antibodies
Complications
The key complications of antiphospholipid syndrome are:
- Venous thromboembolism (e.g., deep vein thrombosis and pulmonary embolism)
- Arterial thrombosis (e.g., stroke, myocardial infarction and renal thrombosis)
- Pregnancy-related complications (e.g., recurrent miscarriage, stillbirth and pre-eclampsia)
Catastrophic antiphospholipid syndrome is a rare complication with rapid thrombosis in multiple organs within a few days. This has a high mortality rate.
TOM TIP: In your exams, look out for the patient with thrombosis (e.g., deep vein thrombosis or stroke) and a history of recurrent miscarriage. The diagnosis is likely antiphospholipid syndrome.
Associations
Livedo reticularis is a purple lace-like (reticular) rash that gives a mottled appearance to the skin. A more permanent version of this rash, called livedo racemosa, is associated with antiphospholipid syndrome.
Libmann-Sacks endocarditis is a non-bacterial endocarditis with growths (vegetations) on the heart valves (most often the mitral and aortic valves). It is associated with SLE and antiphospholipid syndrome.
Thrombocytopenia (low platelets) is common in antiphospholipid syndrome.
Management
Diagnosis is based on clinical features and persistent antiphospholipid antibodies.
Long-term warfarin with a target INR of 2-3 is used to prevent thrombosis.
Low molecular weight heparin (e.g., enoxaparin) and aspirin are used in pregnancy to reduce the risks. Warfarin is contraindicated in pregnancy.
Last updated August 2023
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