Antiphospholipid syndrome (APS) is an autoimmune disorder that is characterized by the presence of antiphospholipid antibodies that target phospholipids in the blood. This disorder is known to cause various clinical features such as thrombosis, recurrent miscarriages and thrombocytopenia. Additionally, it can be associated with other diseases such as systemic lupus erythematosus and HIV infection.
Clinical Features
The clinical presentation associated with antiphospholipid syndrome is highly variable and can include thrombosis, recurrent miscarriages, skin lesions, thrombocytopenia, venous and arterial thromboses, pulmonary emboli, stroke and cognitive decline. Additionally, patients may present with low platelet count, along with dilated scalp veins called livedo reticularis.
Pathophysiology
The pathophysiology of APS involves the production of an abnormally high number of antiphospholipid antibodies. These antibodies are targeted against phospholipids found on cell surfaces and in the membrane of the blood vessels. This leads to an increased risk of thrombosis due to a prothrombotic state, recurrent miscarriage due to a hypercoagulable state, and tissue injury due to an inflammation-induced damage.
Laboratory Testing
In order to diagnose APS, a detailed clinical history must be taken and laboratory tests should be done to measure the levels of antiphospholipid antibodies in the blood. The most commonly used tests for this purpose are Anticardiolipin antibodies (aCL) IgG and IgM, Lupus anticoagulant tests, and Beta-2-glycoprotein 1 IgG and IgM antibodies. A positive result obtained from any one of these tests suggests a diagnosis of APS.