What is Anti Cardiolipin Antibody IgM (ACL)?
Also Known As: Anticardiolipin Antibodies, aCL Antibody
Formal Name: Cardiolipin Antibodies (IgG, IgM and IgA)
Cardiolipin antibodies are autoantibodies produced by the immune system that mistakenly target the body’s own cardiolipins, substances found in the outermost layer of cells (cell membranes) and platelets. These autoantibodies can affect the body’s ability to regulate blood clotting in a way that is not well understood. This test detects the presence of cardiolipin antibodies in the blood.
Cardiolipins, and other related phospholipids, are lipid molecules that play an important role in the blood clotting process. Cardiolipin antibodies target cardiolipins and are associated with an increased risk of developing recurrent inappropriate blood clots (thrombi) in veins and arteries, such as the deep veins of the legs (DVT) or the lungs (pulmonary embolism, PE). They may also be associated with a low platelet count (thrombocytopenia), recurrent miscarriages (especially in the second and third trimester), and with premature labor and pre-eclampsia.
Cardiolipin antibodies are the most common antiphospholipid antibody, a group of autoantibodies associated with excessive clotting and autoimmune diseases, such as lupus. They are frequently detected with other antiphospholipid antibodies, such as lupus anticoagulant and anti-beta-2 glycoprotein 1. They may also be detected temporarily in people with acute infections, HIV/AIDS, some cancers, with drug treatments (such as phenytoin, penicillin, and procainamide), and in the elderly.
When an individual has inappropriate blood clot formation, recurrent miscarriages, cardiolipin antibodies, and/or another antiphospholipid antibody, the person may be diagnosed with antiphospholipid syndrome (APS). APS can be primary or secondary. Primary APS is not necessarily associated with a related autoimmune disorder, while secondary APS is associated with an autoimmune disorder.
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.
How is it used?
Tests for cardiolipin antibodies are frequently used to help determine the cause of:
- An unexplained blood clot (thrombotic episode)
- Recurrent miscarriages
- A prolonged result on the coagulation (clotting test) PTT (partial thromboplastin time); in this setting, the test is often ordered along with lupus anticoagulant testing (e.g., dilute Russell viper venom test, DRVVT)
If cardiolipin antibodies are detected on an initial test, then it is usually repeated 12 weeks later to help determine whether their presence is persistent or temporary. If a person with a known autoimmune disorder tests negative for cardiolipin antibodies, they may be retested later as these antibodies may develop at any time in the future.
There are three classes of cardiolipin antibodies that may be present in the blood: IgG, IgM and/or IgA. The two most commonly tested are IgG and IgM. However, if these tests are negative and clinical suspicions still exist, then IgA cardiolipin antibody testing may be ordered.
Some other tests that may be performed in conjunction with cardiolipin antibody tests include lupus anticoagulant testing (e.g., DRVVT) and anti-beta-2 glycoprotein 1 antibody.
