Lupus anticoagulants are found in people with autoimmune diseases, such as systemic lupus erythematosis (SLE) and also in those taking certain medications, such as phenothiazines, phenytoin, dilantin, hydralazine, quinine, amoxicillin, and oral contraceptives. They may also be present in patients with inflammatory bowel disease, infections, and some tumors.

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.

• 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.

The outcome is usually good with appropriate therapy. Some patients have difficult-to-control clots, with recurrent symptoms.

• Stroke
• Heart attack
• Blood clot in lungs (pulmonary embolism)

Call your health care provider if you notice symptoms of clot -- 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.

Harris ED, Budd RC, Genovese MC, Firestein GS, Sargent JS, Sledge CB. Kelley's Textbook of Rheumatology. 7th ed. St. Louis, Mo: WB Saunders; 2005.