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Lupus Anticoagulant

Does this test have other names?

LA, Lupus Anticoagulant Panel, Lupus Inhibitor, LA Sensitive PTT, PTT-LA, Dilute Russell Viper Venom Test, DRVVT, Modified Russell Viper Venom Test, MRVVT 

What is this test?

This is a specialized blood test to determine whether your body is producing certain antibodies or proteins that cause you to have a blood-clotting disorder. It does not mean you have lupus, specific type of autoimmune disorder.

Antibodies are proteins in the blood that help you fight off foreign invaders such as viruses and bacteria. Lupus antibodies are one of two types of antiphospholipid antibodies that are sometimes found in blood. Antiphospholipid antibodies are proteins that react to the phospholipids, or fat molecules, normally found in the membranes of blood cells. Antiphospholipids can interfere with the work of your blood cells and cause blood vessels to narrow and clots to form. Clots can lead to heart attacks, strokes, pulmonary embolisms, and deep vein thromboses, which occur when blood clots form in the deep veins of the body.

These antibodies are called lupus antibodies because they were first discovered to be related to lupus. Not everyone who has lupus has these antibodies, however. And people who don't have lupus can start producing them. The reason is unknown. 

Why do I need this test?

You might have this test if you develop blood clots that can't be explained, suffer repeated miscarriages, or have other blood tests that show your blood takes a long time to clot. You might be asked to repeat the test if the lupus anticoagulant is found in your blood. Repeat testing will help determine whether the condition is temporary or persistent. 

What other tests might I have along with this test?

If your test results are positive, your doctor is likely to order additional, specialized blood-clotting tests. They might include:

  • Repeating the test

  • Activated partial thromboplastin time

  • Anticardiolipin antibody

  • Modified Russell viper venom time, or MRVVT

  • Platelet neutralization procedure, or PNP

  • Kaolin clotting time, or KCT

  • Coagulation factor assays

  • Complete blood cell count, or CBC 

What do my test results mean?

A result for a lab test may be affected by many things, including the method the laboratory uses to do the test. If your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

The test results will show whether lupus anticoagulant antibodies are present in the blood. If your test shows they are, it should be repeated in several weeks to confirm.

Normal values are:

  • Less than 23 GPL (IgG phospholipid units)

  • Less than 11 MPL (IgL phospholipid units)

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm. 

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, and a sense of lightheadedness. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Your blood sample should be collected before you begin taking anticoagulation medications, because they can skew the results.

Tell your doctor if you are taking any other drugs because they might interfere with your test results. If you have an infection or cancer, it can affect your test results.  

If the lab where the LA test is done is inexperienced with the test, it could result in false positives.

How do I get ready for this test?

You do not need to prepare for this test.