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Antiphospholipid Antibodies

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Also known as: APA
Formal name: Antiphospholipid Antibodies
Related tests: Lupus Anticoagulant Testing, Cardiolipin Antibodies, PTT, Platelet Neutralization Procedure, Kaolin Clotting Time, Hexagonal Phospholipid Confirmatory Test, Dilute Prothrombin Time, Beta-2 Glycoprotein 1 Antibodies, Antiphosphatidylserine Antibodies, Antiprothrombin Antibodies

The Test Sample

What is being tested?

Antiphospholipid antibodies are immune proteins that the body mistakenly produces against itself in an autoimmune response to phospholipids. These tests detect these autoantibodies that bind to phospholipids and, in a way that is not well understood, increase the risk of excessive blood clotting.

Several tests are available, including:

Phospholipids are a normal part of the body. They are lipid molecules found in the outer-most layer of cells (cell membranes) and platelets and they play a crucial role in blood clotting. When antiphospholipid antibodies are produced, they interfere with the clotting process. They increase an affected person's risk of developing recurrent inappropriate blood clots (thrombi) in arteries and veins, which can lead to strokes and heart attacks. Antiphospholipid antibodies are also associated with low platelet counts (thrombocytopenia) and with the risk of recurrent miscarriages (especially in the second and third trimester), premature labor, and preeclampsia.

One or more antiphospholipid antibodies are frequently seen with autoimmune disorders such as systemic lupus erythematosus (SLE), also called lupus. They may also be seen with HIV, some cancers, in the elderly, and temporarily with infections and with some drug treatments (such as phenothiazines and procainamide).

Antiphospholipid syndrome (APS), also called Hughes syndrome, is a recognized group of signs and symptoms that includes the formation of thrombi, miscarriages, thrombocytopenia, and the presence of one or more antiphospholipid antibodies. APS can be primary with no underlying autoimmune disorder or secondary, existing with a diagnosed autoimmune disorder.

The most common tests for detecting antiphospholipid antibodies are cardiolipin antibodies and lupus anticoagulant assays. Others that are not as frequently used include beta2 glycoprotein I antibodies and anti-phosphatidylserine antibodies.

Lupus anticoagulant assays include RVVT (Russell viper venom time) and hexagonal phase lipid neutralization; platelet neutralization procedure can also be used to confirm lupus anticoagulant but is less commonly used nowadays.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.