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 test for lupus, a specific type of an 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 in various parts of your body, such as your heart, brain, lungs, and legs.

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 may need 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:

  • Activated partial thromboplastin time

  • Anticardiolipin antibody

  • Modified Russell viper venom time

  • Platelet neutralization procedure

  • Kaolin clotting time

  • Coagulation factor assays

  • Complete blood cell count

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

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

If you have lupus or another autoimmune disease, and the test results are negative, your healthcare provider may want to repeat the test at a later date to determine if the anticoagulant antibodies have begun to develop. 

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

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

Tell your healthcare provider if you are taking any other medicines because they might interfere with your test results. Infection or cancer can also 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 don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you take. This includes medicines that don't need a prescription and any illegal drugs you may use.