Lupus anticoagulants

Lupus anticoagulants are antibodies against phospholipids (a group of substances in cell membranes) which inhibit blood clotting in a test tube, but may be associated with a higher risk of clotting in people who have them in their blood.

Causes, incidence, and risk factors

Lupus anticoagulants are found in people with auto-immune diseases, such as systemic lupus erythematosis (SLE) and also in those taking certain medications, such as phenothiazines.

Some people with these antibodies have no clear, predisposing factor. In some cases, the condition is associated with an increased risk of blood clots and it may be the cause of recurrent miscarriages.


  • Blood clots in veins  
  • Blood clots in arteries  
  • Recurrent miscarriages

The condition can also occur with no symptoms.

Signs and tests

  • Elevated PTT  
  • Abnormal tissue thromboplastin inhibition test  
  • Prolonged dilute Russell viper venom time

No treatment is required in the absence of symptoms. If clots occur, patients should be anticoagulated with heparin followed by warfarin. Higher than usual doses of warfarin may be required. Steroids are sometimes effective in decreasing the level of antibody, but it is not clear whether this decreases clotting risk.

Expectations (prognosis)
The outcome is usually good with appropriate therapy. Some patients have difficult to control clots, with recurrent symptoms.


Calling your health care provider
Call your health care provider if you notice symptoms of clot, such as swelling or redness in the leg; shortness of breath; or pain, numbness and pallor in an extremity.

Awareness of risk factors may allow early diagnosis. Prevention may not be possible.

Johns Hopkins patient information

Last revised: December 5, 2012
by Potos A. Aagen, M.D.

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