What Is Antiphospholipid Antibody Syndrome?

Antiphospholipid (AN-te-fos-fo-LIP-id) antibody syndrome (APS) is an autoimmune disorder. Autoimmune disorders occur when the immune system makes antibodies that attack and damage the body’s tissues or cells by mistake. Antibodies are a type of protein that the immune system usually makes to defend against infection.

In APS, the body mistakenly makes antibodies that attack phospholipids—a type of fat. Phospholipids are found in all living cells and cell membranes, including blood cells and the lining of blood vessels.

When antibodies attack phospholipids, they damage cells. This causes unwanted blood clots to form in the body’s arteries and veins. (These are the vessels that carry blood to your heart and body.)

Usually, blood clotting is a normal bodily process. Blood clots help seal small cuts or breaks and prevent you from losing too much blood. In APS, however, too much blood clotting can block blood flow and damage the body’s organs.

Overview

Some people have APS antibodies, but don’t ever have signs or symptoms of the disorder. The presence of APS antibodies, by itself, doesn’t mean that you have APS. To be diagnosed with APS, you must have APS antibodies and a history of health problems related to the disorder.

APS can lead to a number of health problems, such as stroke, heart attack, kidney damage, deep vein thrombosis (throm-BO-sis), pulmonary embolism (PULL-mun-ary EM-bo-lizm), or pregnancy-related problems.

Pregnancy-related problems may include multiple miscarriages, a miscarriage late in pregnancy, or a premature birth due to eclampsia. (Eclampsia, which follows preeclampsia, is a serious condition that causes seizures in pregnant women.)

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

People who have APS also are at higher risk for thrombocytopenia (THROM-bo-si-to-PE-ne-ah). This is a condition in which your blood has a low number of blood cells called platelets (PLATE-lets). This can lead to mild to serious bleeding.

In APS, thrombocytopenia occurs because the platelets are used up by the clotting process or because antibodies destroy them.

In some cases, APS can be fatal. This may occur due to large blood clots or blood clots in the heart, lungs, or brain.

Outlook

APS can affect people of any age. However, it’s more common in women and people who have other autoimmune or rheumatic disorders, such as lupus. ("Rheumatic" refers to disorders that affect the joints, bones, or muscles.)

APS has no cure, but medicines can help prevent its complications. Medicines are used to stop blood clots from forming and keep existing clots from getting larger. Treatment for the disorder is long term.

If you have APS and another autoimmune disorder, it’s important to control that condition as well. When the other condition is controlled, APS may cause fewer problems.

September 2008