What is Antiphospholipid Antibody Syndrome?

Antiphospholipid syndrome (APS) is an autoimmune disease which can cause frequent clotting in arteries and veins and/or miscarriages.

In APS the body makes antibodies called anti-phospholipid autoantibodies that attack phospholipids, fats found in all living cells. When antibodies attack phospholipids, cells are damaged. This damage causes excessive clotting, allowing blood clots to form in the body's arteries and veins.

Who gets APS?
APS can affect people of any age.  However, it affects women five times more than men and is more common in people with other autoimmune disorders, such as lupus.  It is typically diagnosed between the ages of 30 and 40. Up to 40% of patients with SLE have anti-phospholipid autoantibodies but only 20% will develop thrombosis and/or experience miscarriages.

What are the potential complications of Antiphospholipid Antibody Syndrome?
Too much blood clotting can lead to thrombosis, meaning that a clot is blocking the flow of blood through the body. Resulting organ damage can depend on where the clot forms.
For instance, clots in the heart can lead to a heart attack while stroke can result from blood clots in the arteries in the brain. Clots forming in the veins, most commonly in the legs, can break off and travel to the lung, causing pulmonary embolism which blocks blood flow to the lung and decreases the amount of oxygen in the blood.  A condition called thrombocytopenia can also occur when the antibodies destroy blood platelets causing mild to serious bleeding.

APS also can cause pregnancy-related problems, such as miscarriage or a premature birth.

Very rarely, some people who have APS develop many blood clots within weeks or months. This condition is called catastrophic antiphospholipid syndrome (CAPS).

How is APS diagnosed?
APS is diagnosed when a person has thrombosis and/or more than one miscarriage. Blood tests can detect the antiphospholipid autoantibodies.

How is APS treated?
APS has no cure, but currently medicines are used to stop blood clots from forming or to keep existing clots from getting larger.

American College of Rheumatology
NIH National Heart, Lung and Blood Institute