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Antiphospholipid Antibodies

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Also known as: APA; Phospholipid Antibodies
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, Antiprothrombin Antibodies, ANA

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The Test Sample

What is being tested?

Antiphospholipid antibodies are a group of immune proteins (antibodies) that the body mistakenly produces against itself in an autoimmune response to phospholipids. Tests can 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 structural components of cell membranes and play a crucial role in blood clotting. Phospholipds are critical to platelet function in addition to various coagulation co-factors. 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, heart attacks, and/or miscarriages.

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 pre-eclampsia.

One or more antiphospholipid antibodies have been identified in various conditions. Some examples are:

Autoimmune disorders



Use of certain drugs

  • Procainamide
  • Phenothiazines
  • Oral contraceptives

The presence of phospholipid antibodies in some instances may be temporary and they have been identified in some individuals who have no detectable illnesses.

Antiphospholipid syndrome (APS), also called Hughes syndrome, is a recognized group of signs and symptoms that includes the formation of blood clots, miscarriages, platelet deficiency (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 14th International Congress on Antiphospholipid Antibodies Task Force criteria for identifying APS requires testing for cardiolipin antibodies, lupus anticoagulant, and beta-2 glycoprotein antibodies when one of two clinical problems exist, blood clots (thrombosis) or pregnancy morbidity.

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.