Beta-2 Glycoprotein 1 Antibodies
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
A blood sample drawn from a vein in your arm
Beta-2 glycoprotein 1 antibody is an autoantibody that is associated with inappropriate blood clotting. This test detects and measures one or more classes (IgG, IgM, or IgA) of beta-2 glycoprotein 1 antibodies.
Beta-2 glycoprotein antibody is considered one of the primary autoantibodies called antiphospholipid antibodies that mistakenly target the body's own lipid-proteins (phospholipids) found in the outermost layer of cells (cell membranes) and platelets. This test is often ordered along with those for the other antiphospholipid antibodies, cardiolipin antibody and lupus anticoagulant.
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 people with the autoimmune disorder called antiphospholipid syndrome (APS), which is 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 second and third trimesters.
One or more antiphospholipid antibodies may also be seen with other autoimmune disorders, such as lupus (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.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
How is it used?
Beta-2 glycoprotein 1 antibody tests are used along with cardiolipin antibody and lupus anticoagulant testing to help diagnose the cause of an unexplained blood clot (thrombotic episode) or recurrent miscarriages, to help diagnose antiphospholipid syndrome (APS), or to detect the autoantibodies in someone with another autoimmune disorder.
Antiphospholipid antibodies, including beta-2 glycoprotein anitboides, are associated with excessive clotting. They interfere with the body's blood clotting process in a way that is not fully understood. (See the "What is being tested?" section for more.)
As beta-2 glycoprotein 1 antibody is less common than the other antiphospholipid antibodies, it may be ordered as a follow-up to those tests to provide a health practitioner with additional information. However, beta 2 glycoprotein 1 antibodies have been reported to be more specific (but less sensitive) than cardiolipin antibodies for the diagnosis of APS.
Laboratory tests can detect three different classes of these autoantibodies: IgG, IgM, and IgA. 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 laboratory criteria for APS diagnosis.
If a beta-2 glycoprotein 1 antibody is detected, the same test will be repeated about 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 ordered?
Beta-2 glycoprotein 1 antibody tests and other antiphospholipid antibody testing may be ordered when a person's symptoms suggest a blood clot in a vein or artery. Symptoms may include pain and swelling in the extremities, shortness of breath, and headaches.
Beta-2 glycoprotein 1 antibody tests may also be ordered when a woman has had recurrent miscarriages or when a person has signs and symptoms of antiphospholipid syndrome (APS), such as:
- Persistent headaches
- Pregnancy complications such as pre-eclampsia
- Chest pain
- Shortness of breath
- Speech and/or cognitive changes
- Memory loss
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?
A positive beta-2 glycoprotein 1 antibody test may indicate that the person has antiphospholipid syndrome (APS), as they are most frequently seen with the condition. Current diagnostic criteria for APS are based upon both clinical findings and the persistent presence of one or more antiphospholipid antibodies. If a high level of beta-2 glycoprotein 1 antibody is detected initially and then again 12 weeks later in a person with signs of APS, then it is likely that the person has the disorder. This is especially true if other antiphospholipid antibodies are also detected.
If the test 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 with 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. That is why a diagnosis of APS requires clinical symptoms plus at least two positive tests for an antiphospholipid antibody at least 12 weeks apart.
Is there anything else I should know?
One or more antiphospholipid antibodies may be present with a variety of autoimmune disorders. (See the article on Autoimmune Disorders for a list of examples.) A person may also have co-existing autoimmune disorders, such as both antiphospholipid syndrome (APS) and lupus.
Should everyone have antiphospholipid testing?
No, this testing is not intended to be a screening tool for the general population. Most people will never need to have this testing performed.
Can beta-2 glycoprotein 1 antibody testing be performed in my doctor's office?
No, this testing requires specialized equipment and must be done in a laboratory.
If I have antiphospholipid antibodies, will I definitely develop blood clots?
Not necessarily. They represent a risk factor but cannot predict whether an individual person will have recurrent blood clots. And, if a person does, the presence of the antibodies cannot predict the frequency or severity of clotting.
Should I tell a new doctor that I have antiphospholipid antibodies?
Yes, this is an important part of your medical history. Your doctor needs this information even if you don't have symptoms in order to tailor any procedures or medical treatment plans around this risk factor.
On This Site
Elsewhere On The Web
American Autoimmune Related Diseases Association: Autoimmune Disease in Women
APS Foundation of America, Inc.: Antiphospholipid Antibody Syndrome
National Human Genome Research Institute: Learning About Antiphospholipid Syndrome (APS)
Lupus Foundation of America: What are antiphospholipid antibodies?