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How Is Antiphospholipid Antibody Syndrome Diagnosed?

Your doctor will diagnose antiphospholipid antibody syndrome (APS) based on your medical history and the results from blood tests.

Specialists Involved

A hematologist often is involved in the care of people who have APS. This is a doctor who specializes in diagnosing and treating blood diseases and disorders.

You may have APS and another autoimmune disorder, such as lupus. If so, a doctor who specializes in that disorder also may provide treatment.

Many autoimmune disorders that occur with APS also affect the joints, bones, or muscles. Rheumatologists specialize in treating these types of disorders.

Medical History

Some people have APS antibodies but no signs or symptoms of the disorder. Having APS antibodies doesn't mean that you have APS. To be diagnosed with APS, you must have APS antibodies and a history of health problems related to the disorder.

APS can lead to many health problems, including stroke, heart attack, kidney damage, deep vein thrombosis, and pulmonary embolism.

APS also can cause pregnancy-related problems, such as multiple miscarriages, a miscarriage late in pregnancy, or a premature birth due to eclampsia. (Eclampsia, which follows preeclampsia, is a serious condition that causes seizures in pregnant women.)

Blood Tests

Your doctor can use blood tests to confirm a diagnosis of APS. These tests check your blood for any of the three APS antibodies: anticardiolipin, beta-2 glycoprotein I (β2GPI), and lupus anticoagulant.

The term "anticoagulant" (AN-te-ko-AG-u-lant) refers to a substance that prevents blood clotting. It may seem odd that one of the APS antibodies is called lupus anticoagulant. The reason for this is because the antibody slows clotting in lab tests. However, in the human body, it increases the risk of blood clotting.

To test for APS antibodies, a small blood sample is taken. It's often drawn from a vein in your arm using a needle. The procedure usually is quick and easy, but it may cause some short-term discomfort and a slight bruise.

You may need a second blood test to confirm positive results. This is because a single positive test can result from a short-term infection. The second blood test often is done 12 weeks or more after the first one.

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Antiphospholipid Antibody Syndrome Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Antiphospholipid Antibody Syndrome, visit

May 17, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.