Share this page
Print this article
Was this page helpful?

Cardiolipin Antibodies

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 Testing

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 second and third trimesters

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

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 labor and preeclampsia.

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.

When a patient has thrombi 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 or secondary, existing with a diagnosed 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

How is it used?

Tests for IgG and IgM cardiolipin antibodies are frequently ordered to help determine the cause of an unexplained thrombotic episode, recurrent miscarriage, or thrombocytopenia. They may be ordered along with lupus anticoagulant testing to help investigate the cause of a prolonged PTT (activated partial thromboplastin time), especially if clinical findings suggest that the patient may have SLE or another autoimmune disorder. If the primary test results are unremarkable but clinical suspicions still exist, then IgA cardiolipin antibody testing may be ordered.

If one or more of the classes of cardiolipin antibodies is detected, then the same test(s) are usually repeated at least 6 weeks apart to help determine whether their presence is persistent or temporary. If a patient 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.

^ Back to top

When is it ordered?

Cardiolipin antibody testing may be ordered when a patient has symptoms suggestive of a thrombotic episode, such as pain and swelling in the extremities, shortness of breath, or headaches. It may also be ordered when a woman has had recurrent miscarriages, and/or ordered along with lupus anticoagulant testing as a follow-up to a prolonged PTT test. When an IgG, IgM, and/or IgA cardiolipin antibody is detected, then it may be repeated several weeks later to determine whether the antibody is temporary or persistent.

If cardiolipin antibodies are not detected in a patient with an autoimmune disorder, such as SLE, tests may be ordered in the future to screen for their development.

^ Back to top

What does the test result mean?

A negative result means only that the cardiolipin antibody class tested (IgG, IgM, and/or IgA) is not present at this time. Since cardiolipin antibodies are the most common of the antiphospholipid antibodies, it is not unusual to find them emerging, temporarily due to an infection or drug, or asymptomatically as a person ages. The low to moderate concentrations of antibody seen in these situations are frequently not significant, but they must be examined in conjunction with a patient’s symptoms and other clinical information.

Moderate to high levels of one or more of the classes of cardiolipin antibodies that persist when tested again 6 weeks later indicate the likely continued presence of that specific antibody.

^ Back to top

Is there anything else I should know?

Occasionally, cardiolipin testing may be ordered to help determine the cause of a positive VDRL/RPR test for syphilis. The reagents used to test for syphilis contain phospholipids and can cause a false positive result in patients with cardiolipin antibodies.

^ Back to top

Common Questions

1.  If I have anticardiolipin antibodies, will I definitely develop blood clots?

Not necessarily. The cardiolipin antibodies represent a risk factor, but they cannot predict whether an individual person will have recurrent blood clots or other associated complications. And, if a person does have blood clots, the presence of the antibodies cannot predict their frequency or severity.

^ Back to top

2.  Should I tell a new doctor that I have anticardiolipin antibodies?

Yes, this is an important part of your medical history. Your doctor needs this information even if you are asymptomatic so that they can tailor any procedures or medical treatment plans around this risk factor.

^ Back to top

Ask a Laboratory Scientist

This form enables you to ask specific questions about your tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. If your questions are not related to your lab tests, please submit them via our Contact Us form. Thank you.

* indicates a required field




  Patient, Family member or Friend
  Laboratorian or Other Medical Professional
  Other



You must provide a valid email address in order to receive a response.



| Read The Disclaimer


Spam Prevention

| |

Article Sources

« Return to Related Pages

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

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosbys 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 http://www.apsfa.org/aps.htm. Accessed on 4/20/08.

(2008 February 5, Reviewed). Learning About Antiphospholipid Syndrome (APS). National Human Genome Research Institute. Available online at http://www.genome.gov/17516396. Accessed on 4/20/08.

Sources Used in Previous Reviews

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

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosbys 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 http://www-admin.med.uiuc.edu/hematology/PtAPS.htm through http://www-admin.med.uiuc.edu.

(© 2004). Antiphospholipid Testing. ARUP's Guide to Clinical Laboratory Testing. Available online at http://www.arup-lab.com/guides/clt/tests/clt_al67.jsp#3965115 through http://www.arup-lab.com.

Petri, M. (2001). Antiphospholipid Antibodies: Anticardiolipin Antibodies and the Lupus Anticoagulant in Systemic Lupus Erythematosus. The Lupus Foundation of America. Available online at http://www.lupus.org/education/brochures/antiphos02.html through http://www.lupus.org.

(© 2004). Cardiolipin Antibodies, IgG and IgM. ARUP's Guide to Clinical Laboratory Testing. Available online at http://www.arup-lab.com/guides/clt/tests/clt_a133.jsp#1059158 through http://www.arup-lab.com.

The Thrombophilias and Pregnancy. March of Dimes, Professionals and Researchers, Quick References and Fact Sheets. Available online at http://www.marchofdimes.com/professionals/681_9264.asp through http://www.marchofdimes.com.

(2003 September, Modified) Anticardiolipin antibodies (IgG, IgM, IgA). Clinical Coagulation Laboratory Coagulation Test Descriptions. Available online at http://pathology.mc.duke.edu/coag/TestDes.htm through http://pathology.mc.duke.edu.

Carsons, S. et. al. (2004 August 18, Updated). Antiphospholipid Syndrome. EMedicine. Available online at http://www.emedicine.com/med/topic2923.htm through http://www.emedicine.com.

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