Antiphospholipid syndrome (APS) is an autoimmune disorder in which the immune system attacks a special kind of fat cell called a phospholipid. These cells are an important part of cell membranes. An autoimmune disorder is one in which the immune system mistakenly identifies normal, "self" tissues as "non-self" antigens and mounts an immune response against them in an attempt to destroy them.

APS is characterized by a number of problems, including increased tendency for blood clots and stroke, heart valve disorders, miscarriages, and low platelet counts (thrombocytopenia). The risk of these problems is significantly reduced with treatment, which includes anticoagulants and aspirin. Because it is unclear why the condition develops, preventive strategies are unknown.

Antiphospholipid syndrome (APS) is a type of autoimmune disorder in which antibodies attack the body’s own phospholipids (a type of fat that is an important part of cell membranes). The underlying reason that antibodies are directed at the body's own phospholipids is unknown, and the exact mechanism of action is also unclear. Currently, many researchers believe that antiphospholipid antibodies are first created, for unknown reasons, in response to exposure to an infectious agent, such as a bacteria or virus. The full-blown syndrome develops after a "second hit" that triggers the antibodies. The second hit may include smoking, immobilization, pregnancy, oral contraceptives, hormone replacement therapy, cancer, high blood pressure and high cholesterol.

When this condition occurs by itself, it is referred to as primary APS. If the condition involves multiple organ systems, it is referred to a catastrophic APS, a more serious form of the disease. It is also associated with lupus, certain rheumatic diseases and infections, and drug use. Without treatment, people with APS are at increased risk for:

• Recurrent episodes of deep vein thrombosis (DVT). DVT is the formation of an obstructing blood clot in the deep veins embedded in the muscles, usually in the lower leg and sometimes in the lower abdomen or groin. Though DVT may cause swelling and pain in the leg, it may not cause any symptoms. DVT carries a high risk of either the whole blood clot or a piece of the blood clot breaking off and traveling through the bloodstream. If the traveling material lodges in one of the arteries of the lungs, then a potentially fatal pulmonary embolism could occur.
  
  
• Recurrent miscarriages. Since APS was identified, treatment has significantly improved a pregnant APS patient’s chances of carrying a fully developed, healthy baby to term.
  
  
• The formation of blood clots in an artery. If blood clots form in the cerebral arteries leading to the brain, the patient is at increased risk of stroke – a life-threatening event in which the blockage prevents adequate blood flow to part of the brain. If blood clots form in the coronary arteries leading to the heart, the patient is at increased risk of a heart attack – a life–threatening event that results in permanent heart damage or death. Blood clots may also form in the peripheral arteries in the arms, legs and other noncardiac areas of the body (peripheral arterial disease).
  
  
  
• Thickening and other deformities of heart valves.
  
  
• Pulmonary hypertension, usually caused by pulmonary embolism caused by the formation of blood clots in the lungs.
  
  
• Nervous system disorders. Individuals with APLS have an increased risk for epilepsy and Guillain-Barré syndrome.
  
  
• Skin disorders. Leg ulcerations and “splinter hemorrhages” (bleeding under the fingernails or toenails) can be associated with APLS.
  
  
• Kidney disorders.
  
  
• Blood disorders, including low blood platelets (thrombocytopenia) or low red blood cell count (anemia).

Symptoms of antiphospholipid syndrome (APS) include:

Other signs and symptoms that have been associated with APS include migraine headaches, Raynaud phenomenon, pulmonary hypertension, heart valve disease and kidney disorders.

If any of these conditions are recurring, it is particularly important to notify a physician. APS is characterized by recurrent episodes, especially of blood vessel disorders. 

In general, the most common treatment for antiphospholipid syndrome (APS) is to take anticoagulants, frequently including heparin followed by warfarin. In some cases, anticoagulant therapy may be augmented by low-dose aspirin. Among patients who cannot tolerate aspirin, the anti-platelet clopidogrel may be prescribed.

These anticoagulants and antiplatelets hopefully prevent the formation of blood clots, which may lead to more serious health concerns. Another medication, hydroxychloroquine, is sometimes prescribed. The exact medication, dosage and length of therapy depends on the nature of the APS and any adverse events, such as stroke or deep vein thrombosis, that may have already occurred.

Patients who have recurrent APS, or have experienced blood clot problems already, may be on lifelong anticoagulant medications. These medications require frequent monitoring to reduce the risk of bleeding while gaining maximum benefit. It is also important to eliminate any risk factors for blood clots, such as smoking, uncontrolled high blood pressure and elevated blood cholesterol levels.

Among pregnant women with APS, the therapy depends on the level of antibodies in the blood. Pregnant women with higher antibody levels may be prescribed low-molecular weight heparin in combination with low-dose aspirin during the first and second trimesters to reduce the risk of miscarriage.

Most of the studies dealing with treatment of APS concentrate on patients who have already experienced recurrent effects of the syndrome, such as multiple miscarriages or several episodes of deep vein thrombosis. The treatment of patients without symptoms (asymptomatic) is a related issue, however. Currently, many physicians recommend low-dose aspirin therapy for APS patients who are not allergic to aspirin. This is recommended because even asymptomatic APS patients are at an increased long-term risk for blood clots.

By contrast, patients who suffer from catastrophic APS will need much more intensive therapy, usually beginning with IV heparin, followed by long-term warfarin and glucocorticoid therapy. Additional medications and therapies, including plasma exchange, may be recommended in an effort to bring down the level of antiautobodies present in the blood.

APS patients may also need to take special precautions when having surgery. Whenever a patient undergoes surgery, there is the possibility of blood clot formation during the surgery or recovery period. To reduce the risk of deep vein thrombosis or a pulmonary embolism, anticoagulants may be prescribed, especially after orthopedic procedures on the hip or knee. After surgery, cuffs that inflate intermittently may be wrapped around the patient’s legs to improve circulation and reduce the risk of blood clots. Patients scheduled for surgery should discuss their risk factors with their physician. In addition, performing calf and leg exercises before surgery and resuming activity as soon as possible after surgery can be helpful in blood clot prevention.

Because it is unclear why APS develops, preventive strategies are unknown. However, individuals with APS autoantibodies are encouraged to reduce other risk factors for stroke by controlling blood pressure, monitoring cholesterol levels, maintaining a healthy weight to avoid type 2 diabetes and stopping smoking.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following antiphospholipid syndrome-related questions:

1. How long have I had this condition?
   
   
2. What other symptoms or abnormalities have I might experienced related to this condition?
   
   
3. What other abnormalities or conditions are associated with this condition?
   
   
4. Does this condition ever spontaneously heal?
   
   
5. Will I be on medication for the rest of my life?
   
   
6. Are there any herbs or dietary supplements I should be aware of because they might increase my tendency to form blood clots?
   
   
7. Will I need regular screening for antibodies or blood clots?
   
   
8. Is there any chance I will suffer a medical emergency because of APS? What kind of emergency?
   
   
9. Can this condition be managed chronically without a major negative impact on my quality of life?
   
   
10. Are there lifestyle changes I have to make, such as avoiding hard exercise or certain foods?