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Cardiolipin Antibodies

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Also known as: Anticardiolipin Antibodies; aCL Antibody
Formal name: Cardiolipin Antibodies (IgG, IgM, and IgA)

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 or sometimes other autoimmune diseases

When to Get Tested?

When you have had one or more unexplained venous or arterial blood clots (thrombotic episodes); when you have had recurrent miscarriages, especially in the second and third trimesters; when you have symptoms consistent with an autoimmune disease

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?


The Test Sample

What is being tested?

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). 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 preeclampsia.

Cardiolipin antibodies are the most common antiphospholipid antibody, a group of autoantibodies associated with excessive clotting and autoimmune diseases, such as Systemic Lupus Erythematosus (SLE). They are frequently detected with other antiphospholid antibodies, such as lupus anticoagulant and anti-beta2 glycoprotein I. 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, that is, not necessarily associated with a secondary or related autoimmune disorder.

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.

The Test

Common Questions

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Article Sources

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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.

Sources Used in Current Review

(© 1995-2012). Test ID: MCLIP81900. Phospholipid (Cardiolipin) Antibodies, IgM, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at through Accessed May 2012.

Rodgers, III, G. et. al. (Updated 2012 January). Antiphospholipid Syndrome – APS. ARUP Consult [On-line information]. Available online at through Accessed May 2012.

(© 2012). Antiphospholipid Antibodies. Lupus Foundation of America [On-line information]. Available online at through Accessed May 2012.

Moake, J. (Revised 2009 June) Thrombotic Disorders. Merck Manual for Healthcare Professionals [On-line information]. Available online through Accessed May 2012.

Berg, T. (Updated 2012 July 9). Antiphospholipid Antibody Syndrome and Pregnancy. Medscape Reference [On-line information]. Available online at through Accessed July 2012.

Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 71-72.

Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, Pg 774.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Pages 69-70.

(2001 June 26). Antiphospholipid Antibody Syndrome. Hematology Resource Page, Patient Resources University of Illinois - Urbana/Champaign, Carle Cancer Center. Available online at through

(© 2004). Antiphospholipid Testing. ARUP's Guide to Clinical Laboratory Testing. Available online at through

Petri, M. (2001). Antiphospholipid Antibodies: Anticardiolipin Antibodies and the Lupus Anticoagulant in Systemic Lupus Erythematosus. The Lupus Foundation of America. Available online at through

(© 2004). Cardiolipin Antibodies, IgG and IgM. ARUP's Guide to Clinical Laboratory Testing. Available online at through

The Thrombophilias and Pregnancy. March of Dimes, Professionals and Researchers, Quick References and Fact Sheets. Available online at through

(2003 September, Modified) Anticardiolipin antibodies (IgG, IgM, IgA). Clinical Coagulation Laboratory Coagulation Test Descriptions. Available online at through

Carsons, S. et. al. (2004 August 18, Updated). Antiphospholipid Syndrome. EMedicine. Available online at through

Arnout J.IS TH Scientic Standardisation Subcommittee Lupus Anticoagulants/Phospholipid dependent antibodies. International Society of Thrombosis and Haemostasis. Boston. July 2002.

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 70-71.

Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 134-135.

(2006 October 15, Revised). Antiphospholipid Antibody Syndrome. APS Foundation of America. Available online at through Accessed on 4/20/08.

(2008 February 5, Reviewed). Learning About Antiphospholipid Syndrome (APS). National Human Genome Research Institute. Available online at through Accessed on 4/20/08.