Lupus anticoagulants and antiphospholipid antibodies


Lupus anticoagulants are antibodies against substances in the lining of cells. These substances prevent blood clotting in a test tube. They are called phospholipids.

People with antibodies to phospholipids (aPL) may have a very high risk of forming blood clots. In spite of the name anticoagulant, there is no increased risk of bleeding.

Alternative Names

Blood clots - lupus anticoagulants; DVT - anticoagulants


This EM Should be displayed at the top of the article section "Causes"

Most often, lupus anticoagulants and aPL are found in people with diseases such as systemic lupus erythematosus (SLE).

Lupus anticoagulants and aPL may also occur if:

Some people have no risk factors for this condition.


You may not have any symptoms even though you have the antibodies. Symptoms that may occur include:

Exams and Tests

Lupus anticoagulant tests may be done. These are blood clotting tests. The antiphospholipid antibodies (aPL) cause the tests to be abnormal in the laboratory.

Types of clotting tests may include:

Tests for antiphospholipid antibodies (aPL) may include:

Your health care provider may check for antiphospholipid antibody syndrome (APS) if:

The positive tests need to be confirmed after 12 weeks. If you have a positive test without other indications of the disease, you will not have the diagnosis of APS.



Often, you will not need treatment if you do not have symptoms or if you have never had a blood clot in the past.

Take the following steps to help prevent blood clots from forming:

You will be prescribed blood-thinning medicines (such as heparin and warfarin) to help prevent blood clots:

You may also need to take blood thinners for 3 to 4 weeks after surgery to lower your risk of blood clots.


In general, you will need long-term treatment with a blood thinner for a long time if you have the APS. Initial treatment may be heparin, either unfractionated or low-molecular heparin. These medicines are given by injection.

In most cases, warfarin (Coumadin), which is given by mouth, is then started. It is necessary to monitor the level of anticoagulation frequently. This is most often done using the INR test.

If you have APS and become pregnant, you will need to be followed closely by a provider expert in this condition. You will not take warfarin during pregnancy, but will be given low-molecular weight heparin instead.

If you have SLE and APS your provider will also recommend that you take hydroxychloroquine.

Outlook (Prognosis)

Most of the time, outcome is good with proper treatment. Some people may have blood clots that are hard to control with treatments. Symptoms may recur.

When to Contact a Medical Professional

Call your provider if you notice symptoms of a blood clot, such as:

Also talk to your provider if you have repeated loss of pregnancy (miscarriage).


Erkan D, Salmon JE, Lockshin MD. Anti-phospholipid syndrome. In: Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. Kelley and Firestein's Textbook of Rheumatology. 10th ed. Philadelphia, PA: Elsevier; 2017:chap 82.

Khamashta MA, Amigo M-C. Antiphospholipid syndrome: overview of pathogenesis, diagnosis, and management. In: Hochberg MC, Silman AJ, Smolen JS, Weinblatt ME, Weisman MH, eds. Rheumatology. 6th ed. Philadelphia, PA: Elsevier Mosby; 2015:chap 139.

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