Antiphospholipid Antibody Syndrome

Reviewed by: HU Medical Review Board | Last reviewed: January 2020

Antiphospholipid antibody syndrome (APS) is a disorder in which the body attacks normal proteins in the blood. The body uses these proteins to control blood clotting. When a person develops APS, they tend to develop blood clots in the arteries and veins, miscarry, or develop thrombocytopenia (low platelet count).

What are antiphospholipid antibodies?

Antiphospholipid antibodies are a group of immune system proteins (antibodies) that the body mistakenly produces. These antibodies cause an autoimmune response to phospholipids (a type of fat molecules found in the cell membrane), meaning these proteins attack and damage the cells. This leads the body to create blood clots.

There are several types of antiphospholipid antibodies, but the most common are:

  • Lupus anticoagulant (LA)
  • Anticardiolipin antibody (aCL)
  • Anti-β2 glycoprotein (anti-ß2 GPI)1-4

What is antiphospholipid antibody syndrome (APS)?

People with lupus who experience complications from antiphospholipid antibodies are said to have antiphospholipid antibody syndrome. About 15 percent to 20 percent of people with lupus develop APS, but people without lupus may also develop the condition.1

Antiphospholipid antibody syndrome may not cause any symptoms until a blood clot forms or pregnancy complications occur. However, APS can be fatal since blood clots in the heart cause heart attacks, blood clots in the brain cause strokes, and blood clots in the lungs cause a pulmonary embolism. Deep vein thrombosis (DVT), a blood clot in the legs, is another serious complication of APS.

Researchers do not yet understand why antiphospholipid antibodies cause blood clots to form. APS is more common in women than in men.2

How is APS diagnosed?

Your doctor may suspect APS if you develop blood clots (thromboses) or experience pregnancy complications such as pre-term birth or miscarriage, or both. Major signs that you may have a blood clot include:

  • Chest pain
  • Shortness of breath
  • Pain, redness, warmth, or swelling in the arms or legs
  • Long-lasting headaches
  • Speech changes
  • Pain or discomfort in the arms, back, neck, and jaw
  • Nausea3-4

Blood tests will reveal the presence of antiphospholipid antibodies. If you test positive for antiphospholipid antibodies and have blood clots or other symptoms of lupus, your doctor will diagnose APS.1

What are the side effects of APS?

People with lupus who also develop antiphospholipid antibody syndrome experience higher rates of tissue and organ damage, and several serious complications, including:

  • Thrombosis (blood clots)
  • Death during or within a year of pregnancy
  • Valve disease
  • Thrombocytopenia (low blood platelet count)
  • Hemolytic anemia (abnormal breakdown of red blood cells)
  • Renal lesions
  • Cognitive impairment (brain fog)1,3

How is APS treated?

There is no cure for antiphospholipid antibody syndrome but medicines can help prevent blood clots from forming. Drugs that may be prescribed for APS include:

Since internal bleeding can be a side effect of blood thinners and aspirin, your doctor will order regular blood tests to check how well your blood is clotting. Overall management of lupus may help prevent APS from creating additional problems for you.

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