Beta-2 Glycoprotein 1 Antibodies
At a Glance
Why Get Tested?
To help investigate inappropriate blood clot formation; to help determine the cause of recurrent miscarriage; as part of an evaluation for antiphospholipid syndrome (APS)
When to Get Tested?
When you have had one or more unexplained blood clots in a vein or artery; when you have had recurrent miscarriages, especially in the second and third trimesters
Sample Required?
A blood sample taken from a vein in your arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
This test detects and measures one or more classes (IgG, IgM, or very rarely IgA) of beta-2 glycoprotein 1 antibodies. Beta-2 glycoprotein 1 antibody is one of three primary antiphospholipid antibodies, which are autoantibodies (produced by the body and act against the body) that target the body’s own lipid-proteins (phospholipids) found in the outermost layer of cells (cell membranes) and platelets. The other two antiphospholipid autoantibodies are anti-cardiolipin antibody (anti-CL) and lupus anticoagulant (LA).
Antiphospholipid antibodies interfere with the body’s blood clotting process in a way that is not fully understood. Their presence increases a person’s risk of developing inappropriate blood clots (thrombi) in both arteries and veins. Antiphospholipid antibodies are most frequently seen in those with antiphospholipid syndrome (APS), an autoimmune disorder associated with blood clots (thrombotic episodes), a low platelet count (thrombocytopenia), or with pregnancy complications such as pre-eclampsia and recurrent miscarriages, especially in the 2nd and 3rd trimesters.
Antiphospholipid antibodies may also be detected in the circulation of patients with other autoimmune disorders, such as systemic lupus erythematosus (SLE).
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 necessary.
The Test
How is it used?
Beta-2 glycoprotein 1 antibody tests are used alongside cardiolipin antibody and lupus anticoagulant testing to help diagnose the cause of unexplained blood clots (thrombotic episodes) or recurrent miscarriages, to help diagnose antiphospholipid syndrome (APS), or as part of the investigation of other autoimmune disorders (e.g. SLE).
If all three of the initial antiphospholipid antibody tests for the IgG and IgM classes are negative, but APS is still suspected, then the IgA class of these antibodies may be tested, along with other less common antiphospholipid antibodies, such as anti-phosphatidylserine and anti-prothrombin. However, the value of testing for the IgA class of antiphospholipid antibodies remains controversial. According to the international consensus statement on APS, the presence of the IgA class (either anticardiolipin antibodies or beta-2 glycoprotein 1 antibodies) does not fulfill the laboratory criteria for diagnosis of APS.
If a beta-2 glycoprotein 1 antibody is detected in the blood, the same test will be repeated 12 weeks later to determine whether its presence is persistent or temporary. If a person with an autoimmune disorder tests negative for antiphospholipid antibodies, testing may be repeated at a later time to determine if the person has begun to produce antibodies, as they may develop at any time in the course of disease.
When is it requested?
Beta-2 glycoprotein 1 antibody tests and other antiphospholipid antibody testing may be requested when a person has symptoms suggestive of a blood clot in a vein or artery, such as pain and swelling in the extremities (hands and feet), shortness of breath, and headaches. They also may be ordered when a woman has had recurrent miscarriages. These tests may be ordered initially, along with cardiolipin antibody and lupus anticoagulant testing, or as follow-up tests.
A beta-2 glycoprotein 1 IgA antibody test may sometimes be ordered when initial antiphospholipid antibody testing for the IgG and IgM class is negative but a diagnosis of APS is still suspected.
When one of the antibody tests is positive, it will be repeated at least 12 weeks later to determine whether the antibody is temporary or persistent.
When a person with an autoimmune disorder tests negative for beta-2 glycoprotein 1 antibody, testing may be repeated periodically to screen for antibody development.
What does the test result mean?
Beta-2 glycoprotein 1 antibodies are most frequently detected in the blood of patients with antiphospholipid syndrome (APS). Current diagnostic criteria for APS are based upon both clinical findings and the persistent presence of one or more antiphospholipid antibodies in the circulation. If a high concentration of beta-2 glycoprotein 1 antibody is detected initially and then again 12 weeks later in a person with signs and symptoms of APS, then it is likely that the person has the disorder. This is especially true if other antiphospholipid antibodies are also detected.
If a person is negative for beta-2 glycoprotein 1 antibodies but positive for other antiphospholipid antibodies and has signs and symptoms, then that person also likely has APS.
If a person is weakly to moderately positive for beta-2 glycoprotein 1 antibodies and weakly positive or negative for other antiphospholipid antibodies, then the antibody presence may be due to a condition other than APS. If subsequent testing is negative, then it is likely that the antibodies were temporary. This may be seen if the patient is suffering from an acute infection.
A single positive beta-2 glycoprotein 1 antibody result is not diagnostic of APS, and a negative result does not rule out antiphospholipid antibody development. They just indicate the presence or absence of the antibody at the time of testing.
If a person with another autoimmune disorder, such as systemic lupus erythematosus (SLE), has beta-2 glycoprotein antibodies present in the circulation, they may increase the risk of developing a clot in a blood vessel.
Is there anything else I should know?
One or more antiphospholipid antibodies may be present with a variety of autoimmune disorders (see article on autoimmune disorders for a list of examples.) A person may also have co-existing autoimmune disorders, such as APS and SLE.
These autoantibodies may also be found temporarily in people with acute infections, HIV/AIDS, some cancers, or with use of drugs such as phenytoin, penicillin, and procainamide.
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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.
