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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 special blood test to find out if your body is making 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. They can cause blood vessels to narrow and clots to form. Clots can lead to heart attacks, strokes, pulmonary embolisms, and deep vein thromboses. These 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. But not everyone who has lupus has these antibodies. And people who don't have lupus can start making them. The reason is unknown. 

Why do I need this test?

You might have this test if you get blood clots that can't be explained. You may also have this test if you have repeated miscarriages, or you have other blood tests that show your blood takes a long time to clot. You might be asked to take this test again if the lupus anticoagulant is found in your blood. Taking the test again will help your healthcare provider find out if the condition is temporary or persistent. 

What other tests might I have along with this test?

If your test results are positive, your healthcare provider is likely to order other special 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 healthcare 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 range from 20 to 39 GPL or MPL 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 medicines, because they can skew the results.

Tell your healthcare provider if you are taking any other medicines 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. 

Medical Reviewers:

  • Taylor, Wanda L, RN, PhD
  • Ziegler, Olivia Walton, MS, PA-C