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Also known as: Anticardiolipin antibodies; aCL antibody
Formal name: Cardiolipin antibodies, IgG, IgM, and IgA
Related tests: Antiphospholipid antibodies, anti-beta2 glycoprotein I, anti-phosphatidylserine, autoantibodies, lupus anticoagulant panel

At a Glance

Why Get Tested?

To help investigate inappropriate blood clot formation, to help determine the cause of recurrent miscarriage, or as part of an evaluation for antiphospholipid syndrome

When to Get Tested?

When you have had one or more unexplained venous or arterial thrombotic episodes; when you have had recurrent miscarriages, especially in the 2nd and 3rd trimesters

Sample Required?

A blood sample drawn from a vein in your arm

The Test Sample

What is being tested?

These tests detect the presence of three classes (IgG, IgM, and/or IgA) of cardiolipin antibodies. Produced by the immune system in response to a perceived threat, these proteins are the most common form of antiphospholipid antibodies. They are acquired autoantibodies that can affect the body's ability to regulate blood clotting in a way that is not well understood.

Cardiolipins, and other related phospholipids, are lipid molecules normally found in cell membranes and platelets. They play an important role in the blood clotting process. When antibodies are produced against cardiolipins, they increase an affected patient's risk of developing recurrent inappropriate blood clots (thrombi) in both arteries and veins. Cardiolipin antibodies are also associated with thrombocytopenia, recurrent miscarriages (especially in the 2nd and 3rd trimester), and with premature labour and pre-eclampsia.

Cardiolipin antibodies are frequently seen with autoimmune disorders, such as systemic lupus erythematosus (SLE), and with other antiphospholipid antibodies, such as lupus anticoagulant. They may also be seen temporarily in patients with acute infections, HIV/AIDS, some cancers, with drug treatments (such as phenytoin, penicillin, and procainamide), and asymptomatically in the elderly.

They may occur in low titre, which has no known clinical significance.

When a patient has blood clot formation, recurrent miscarriages, thrombocytopenia, cardiolipin antibodies, and/or another antiphospholipid antibody, they may be diagnosed with antiphospholipid syndrome (APS). APS can be primary with no underlying autoimmune disorder (50%) or secondary, existing with a diagnosed autoimmune disorder, most commonly SLE.

How is the sample collected for testing?

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


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

No test preparation is needed.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.