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What Is Antiphospholipid Antibody Syndrome?

Antiphospholipid (AN-te-fos-fo-LIP-id) antibody syndrome (APS) is an autoimmune disorder. Autoimmune disorders occur if the body's immune system makes antibodies that attack and damage tissues or cells. 

Antibodies are a type of protein. They usually help defend the body against infections. In APS, however, the body makes antibodies that mistakenly 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, cells are damaged. This damage causes 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 on blood vessel walls. This prevents 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. Having APS antibodies 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 many health problems, such as stroke, heart attack, kidney damage, deep vein thrombosis (throm-BO-sis), and pulmonary embolism (PULL-mun-ary EM-bo-lizm).

APS also can cause pregnancy-related problems, such as multiple miscarriages, a miscarriage late in pregnancy, or a premature birth due to eclampsia (ek-LAMP-se-ah). (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 lower than normal number of blood cell fragments called platelets (PLATE-lets). Antibodies destroy the platelets, or they’re used up during the clotting process. Mild to serious bleeding can occur with thrombocytopenia.

APS can be fatal. Death may occur as a result of 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 (ru-MAT-ik) 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. They also are used to keep existing clots from getting larger. Treatment for APS 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.




Other Names for Antiphospholipid Antibody Syndrome

  • Anticardiolipin antibody syndrome, or aCL syndrome
  • Antiphospholipid syndrome
  • aPL syndrome
  • Hughes syndrome
  • Lupus anticoagulant syndrome



What Causes Antiphospholipid Antibody Syndrome?

Antiphospholipid antibody syndrome (APS) occurs if the body's immune system makes antibodies (proteins) that attack phospholipids.

Phospholipids are a type of fat found in all living cells and cell membranes, including blood cells and the lining of blood vessels. Researchers don’t know what causes the immune system to make antibodies against phospholipids.

APS causes blood clots to form in the body's arteries and veins. Usually, blood clotting is a normal bodily process. It helps seal small cuts or breaks on blood vessel walls. Clotting prevents you from losing too much blood. In APS, however, too much clotting can block blood flow and damage the body's organs.

Researchers don't know why APS antibodies cause blood clots to form. Some believe that the antibodies damage or affect the inner lining of the blood vessels, which causes clotting. Others believe that the immune system makes antibodies in response to blood clots damaging the blood vessels.




Who Is at Risk for Antiphospholipid Antibody Syndrome?

Antiphospholipid antibody syndrome (APS) can affect people of any age. The disorder is more common in women than men, but it affects both sexes.

APS also is more common in people who have other autoimmune or rheumatic disorders, such as lupus. ("Rheumatic" refers to disorders that affect the joints, bones, or muscles.)

About 10 percent of all people who have lupus also have APS. About half of all people who have APS also have another autoimmune or rheumatic disorder.

Some people have APS antibodies, but don't ever have signs or symptoms of the disorder. Having APS antibodies 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.

However, people who have APS antibodies without signs or symptoms are at risk of developing APS. Health problems, other than autoimmune disorders, that can trigger blood clots include:

  • Smoking
  • Prolonged bed rest
  • Pregnancy and the postpartum period
  • Birth control pills and hormone therapy
  • Cancer and kidney disease



What Are the Signs and Symptoms of Antiphospholipid Antibody Syndrome?

The signs and symptoms of antiphospholipid antibody syndrome (APS) are related to abnormal blood clotting. The outcome of a blood clot depends on its size and location.

Blood clots can form in, or travel to, the arteries or veins in the brain, heart, kidneys, lungs, and limbs. Clots can reduce or block blood flow, damaging the body's organs and possibly causing death.

Major Signs and Symptoms

Major signs and symptoms of blood clots include:

  • Chest pain and shortness of breath
  • Pain, redness, warmth, and swelling in the limbs
  • Ongoing headaches
  • Speech changes
  • Upper body discomfort in the arms, back, neck, and jaw
  • Nausea (feeling sick to your stomach)

Blood clots can lead to stroke, heart attack, kidney damage, deep vein thrombosis, and pulmonary embolism.

Pregnant women who have APS are at higher risk for miscarriages, stillbirths, and other pregnancy-related problems, such as preeclampsia.

Preeclampsia is high blood pressure that occurs during pregnancy. This condition may progress to eclampsia. Eclampsia is a serious condition that causes seizures in pregnant women.

Some people who have APS may develop thrombocytopenia. This is a condition in which your blood has a lower than normal number of blood cell fragments called platelets.

Mild to serious bleeding causes the major signs and symptoms of thrombocytopenia. Bleeding can occur inside the body (internal bleeding) or underneath the skin or from the surface of the skin (external bleeding).

Other Signs and Symptoms

Other signs and symptoms of APS include chronic (ongoing) headaches, memory loss, and heart valve problems. Some people who have APS also get a lacy-looking red rash on their wrists and knees.




How Is Antiphospholipid Antibody Syndrome Diagnosed?

Your doctor will diagnose antiphospholipid antibody syndrome (APS) based on your medical history and the results from blood tests.

Specialists Involved

A hematologist often is involved in the care of people who have APS. This is a doctor who specializes in diagnosing and treating blood diseases and disorders.

You may have APS and another autoimmune disorder, such as lupus. If so, a doctor who specializes in that disorder also may provide treatment.

Many autoimmune disorders that occur with APS also affect the joints, bones, or muscles. Rheumatologists specialize in treating these types of disorders.

Medical History

Some people have APS antibodies but no signs or symptoms of the disorder. Having APS antibodies 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 many health problems, including stroke, heart attack, kidney damage, deep vein thrombosis, and pulmonary embolism.

APS also can cause pregnancy-related problems, such as 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.)

Blood Tests

Your doctor can use blood tests to confirm a diagnosis of APS. These tests check your blood for any of the three APS antibodies: anticardiolipin, beta-2 glycoprotein I (β2GPI), and lupus anticoagulant.

The term "anticoagulant" (AN-te-ko-AG-u-lant) refers to a substance that prevents blood clotting. It may seem odd that one of the APS antibodies is called lupus anticoagulant. The reason for this is because the antibody slows clotting in lab tests. However, in the human body, it increases the risk of blood clotting.

To test for APS antibodies, a small blood sample is taken. It's often drawn from a vein in your arm using a needle. The procedure usually is quick and easy, but it may cause some short-term discomfort and a slight bruise.

You may need a second blood test to confirm positive results. This is because a single positive test can result from a short-term infection. The second blood test often is done 12 weeks or more after the first one.




How Is Antiphospholipid Antibody Syndrome Treated?

Antiphospholipid antibody syndrome (APS) has no cure. However, medicines can help prevent complications. The goals of treatment are to prevent blood clots from forming and keep existing clots from getting larger.

You may have APS and another autoimmune disorder, such as lupus. If so, it's important to control that condition as well. When the other condition is controlled, APS may cause fewer problems.

Research is ongoing for new ways to treat APS.

Medicines

Anticoagulants, or "blood thinners," are used to stop blood clots from forming. They also may keep existing blood clots from getting larger. These medicines are taken as either a pill, an injection under the skin, or through a needle or tube inserted into a vein (called intravenous, or IV, injection).

Warfarin and heparin are two blood thinners used to treat APS. Warfarin is given in pill form. (Coumadin® is a common brand name for warfarin.) Heparin is given as an injection or through an IV tube. There are different types of heparin. Your doctor will discuss the options with you.

Your doctor may treat you with both heparin and warfarin at the same time. Heparin acts quickly. Warfarin takes 2 to 3 days before it starts to work. Once the warfarin starts to work, the heparin is stopped.

Aspirin also thins the blood and helps prevent blood clots. Sometimes aspirin is used with warfarin. Other times, aspirin might be used alone.

Blood thinners don't prevent APS. They simply reduce the risk of further blood clotting. Treatment with these medicines is long term. Discuss all treatment options with your doctor.

Side Effects

The most common side effect of blood thinners is bleeding. This happens if the medicine thins your blood too much. This side effect can be life threatening.

Sometimes the bleeding is internal (inside your body). People treated with blood thinners usually need regular blood tests, called PT and PTT tests, to check how well their blood is clotting.

These tests also show whether you're taking the right amount of medicine. Your doctor will check to make sure that you're taking enough medicine to prevent clots, but not so much that it causes bleeding.

Talk with your doctor about the warning signs of internal bleeding and when to seek emergency care. (For more information, go to "Living With Antiphospholipid Antibody Syndrome.")

Treatment During Pregnancy

Pregnant women who have APS can have successful pregnancies. With proper treatment, these women are more likely to carry their babies to term.

Pregnant women who have APS usually are treated with heparin or heparin and low-dose aspirin. Warfarin is not used as a treatment during pregnancy because it can harm the fetus.

Babies whose mothers have APS are at higher risk for slowed growth while in the womb. If you're pregnant and have APS, you may need to have extra ultrasound tests (sonograms) to check your baby’s growth. An ultrasound test uses sound waves to look at the growing fetus.

Treatment for Other Medical Conditions

People who have APS are at increased risk for thrombocytopenia. This is a condition in which your blood has a lower than normal number of blood cell fragments called platelets. Platelets help the blood clot.

If you have APS, you'll need regular complete blood counts (a type of blood test) to count the number of platelets in your blood.

Thrombocytopenia is treated with medicines and medical procedures. For more information, go to the Health Topics Thrombocytopenia article.

If you have other health problems, such as heart disease or diabetes, work with your doctor to manage them.




Living With Antiphospholipid Antibody Syndrome

Antiphospholipid antibody syndrome (APS) has no cure. However, you can take steps to control the disorder and prevent complications.

Take all medicines as your doctor prescribes and get ongoing medical care. Talk with your doctor about healthy lifestyle changes and any concerns you have.

Medicines

You may need to take anticoagulants, or "blood thinners," to prevent blood clots or to keep them from getting larger. You should take these medicines exactly as your doctor prescribes.

Tell your doctor about all other medicines you're taking, including over-the-counter or herbal medicines. Some medicines, including over-the-counter ibuprofen or aspirin, can thin your blood. Your doctor may not want you to take two medicines that thin your blood because of the risk of bleeding.

Women who have APS shouldn't use birth control or hormone therapy that contains estrogen. Estrogen increases the risk of blood clots. Talk with your doctor about other options.

Ongoing Medical Care

If you have APS, getting regular medical checkups is important. Have blood tests done as your doctor directs. These tests help track how well your blood is clotting.

The medicines used to treat APS increase the risk of bleeding. Bleeding might occur inside your body (internal bleeding) or underneath the skin or from the surface of the skin (external bleeding). Know the warning signs of bleeding, so you can get help right away. They include:

  • Unexplained bleeding from the gums and nose
  • Increased menstrual flow
  • Bright red vomit or vomit that looks like coffee grounds
  • Bright red blood in your stools or black, tarry stools
  • Pain in your abdomen or severe pain in your head
  • Sudden changes in vision
  • Sudden loss of movement in your limbs
  • Memory loss or confusion

A lot of bleeding after a fall or injury or easy bruising or bleeding also might mean that your blood is too thin. Ask your doctor about these warning signs and when to seek emergency care.

Lifestyle Changes

Talk with your doctor about lifestyle changes that can help you stay healthy. Ask him or her whether your diet may affect your medicines. Some foods or drinks may increase or decrease the effects of warfarin.

Ask your doctor what amount of alcohol is safe for you to drink if you're taking medicine. If you smoke, talk with your doctor about programs and products that can help you quit. Smoking can damage your blood vessels and raise your risk for many health problems.

APS medicines might increase your risk of bleeding. Thus, your doctor may advise you to avoid activities that have a high risk of injury, such as some contact sports.

Other Concerns

Pregnancy

APS can raise the risk of pregnancy-related problems. Talk with your doctor about how to manage your APS if you're pregnant or planning a pregnancy.

With proper treatment, women who have APS are more likely to carry babies to term than women whose APS isn't treated.

Surgery

If you need surgery, your doctor may adjust your medicines before, during, and after the surgery to prevent dangerous bleeding.




Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. Often, these advances depend on the willingness of volunteers to take part in clinical trials.

Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions. For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you may gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to APS, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.




Links to Other Information About Antiphospholipid Antibody Syndrome

NHLBI Resources

Non-NHLBI Resources

Clinical Trials

 
May 17, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.

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