lupus anti coagulant

What are lupus anticoagulants?

Lupus anticoagulants (LAs) are a type of antibody produced by your body’s immune system. While most antibodies attack disease in the body, LAs attack healthy cells and cell proteins. 

They attack phospholipids, which are essential components of cell membranes. LAs are associated with an immune system disorder known as antiphospholipid syndrome. 

What are the symptoms of lupus anticoagulants?

LAs can increase the risk of blood clots. However, antibodies can be present and not lead to a clot. 

If you develop a blood clot in one of your arms or legs, symptoms may include:

  • swelling in your arm or leg
  • redness or discoloration in your arm or leg
  • breathing difficulties
  • pain or numbness in your arm or leg

A blood clot in the area of your heart or lungs may cause:

  • chest pain
  • excessive sweating
  • breathing difficulties
  • fatigue, dizziness, or both

Blood clots in your stomach or kidneys may lead to:

  • belly pain
  • thigh pain
  • nausea
  • diarrhea or bloody stool
  • fever

Blood clots can be life-threatening if they aren’t treated promptly. 


Small blood clots caused by LAs can complicate a pregnancy and induce miscarriage. Multiple miscarriages may be a sign of LAs, especially if they occur after the first trimester.

Associated conditions

Roughly half of people with the autoimmune disease lupus also have LAs.

How do I get tested for lupus anticoagulants?

Your doctor may order testing for LAs if you have unexplained blood clots or have had multiple miscarriages. 

No single test helps doctors conclusively diagnose LAs. Multiple blood tests are required to determine if LAs are present in your bloodstream. Repeat testing is also needed over time to confirm their presence. This is because these antibodies can appear with infections, but go away once the infection resolves. 

Tests may include:

PTT test

The partial thromboplastin time (PTT) test measures the time it takes your blood to clot. It can also reveal if your blood contains anticoagulant antibodies. However, it won’t reveal whether you specifically have LAs.

If your test results indicate the presence of anticoagulant antibodies, you’ll need to be retested. Retesting normally happens in about 12 weeks.

Other blood tests

If your PTT test indicates the presence of anticoagulant antibodies, your doctor may order other types of blood tests to look for signs of other medical conditions. Such tests may include:

  • anticardiolipin antibody test
  • kaolin clotting time
  • coagulation factor assays
  • dilute Russell viper venom test (DRVVT)
  • LA-sensitive PTT 
  • beta-2 glycoprotein 1 antibody test