Antiphospholipid (AN-te-fos-fo-LIP-id) syndrome occurs when your immune system mistakenly creates antibodies that make your blood much more likely to clot.

This can cause dangerous blood clots in the legs, kidneys, lungs and brain. In pregnant women, antiphospholipid syndrome also can result in miscarriage and stillbirth.

There's no cure for antiphospholipid syndrome, but medications can reduce your risk of blood clots.

Signs and symptoms of antiphospholipid syndrome can include:

• Blood clots in your legs (DVT). Signs of a DVT include pain, swelling and redness. These clots can travel to your lungs (pulmonary embolism).
• Repeated miscarriages or stillbirths. Other complications of pregnancy include dangerously high blood pressure (preeclampsia) and premature delivery.
• Stroke. A stroke can occur in a young person who has antiphospholipid syndrome but no known risk factors for cardiovascular diseases.
• Transient ischemic attack (TIA). Similar to a stroke, a TIA usually lasts only a few minutes and causes no permanent damage.
• Rash. Some people develop a red rash with a lacy, net-like pattern.

Less common signs and symptoms include:

• Neurological symptoms. Chronic headaches, including migraines; dementia and seizures are possible when a blood clot blocks blood flow to parts of your brain.
• Cardiovascular disease. Antiphospholipid syndrome can damage heart valves.
• Bleeding. Some people have a decrease in blood cells needed for clotting. This can cause episodes of bleeding, particularly from your nose and gums. You can also bleed into your skin, which will appear as patches of small red spots.

When to see a doctor

Contact your doctor if you have unexplained bleeding from your nose or gums; an unusually heavy menstrual period; vomit that is bright red or looks like coffee grounds; black, tarry stool or bright red stool; or unexplained abdominal pain.

Seek emergency care if you have signs and symptoms of:

• Stroke. A clot in your brain can cause sudden numbness, weakness or paralysis of your face, arm or leg. You may have difficulty speaking or understanding speech, visual disturbances and a severe headache.
• Pulmonary embolism. If a clot lodges in your lung, you may experience sudden shortness of breath, chest pain and coughing up blood-streaked mucus.
• Deep vein thrombosis (DVT). Signs and symptoms of DVTs include swelling, redness or pain in a leg or arm.

Antiphospholipid syndrome occurs when your immune system mistakenly produces antibodies that make your blood much more likely to clot. Antibodies normally protect the body against invaders, such as viruses and bacteria.

Antiphospholipid syndrome can be caused by an underlying condition, such as an autoimmune disorder, infection or certain medications. You also can develop the syndrome without an underlying cause.

Risk factors for antiphospholipid syndrome include:

• Your sex. This condition is much more common in women than in men.
• Immune system disorders. Having another autoimmune condition, such as lupus or Sjogren's syndrome, increases your risk of antiphospholipid syndrome.
• Infections. This condition is more common in people who have certain infections, such as syphilis, HIV/AIDS, hepatitis C or Lyme disease.
• Medications. Certain medications have been linked to antiphospholipid syndrome. They include hydralazine for high blood pressure, the heart rhythm-regulating medication quinidine, the anti-seizure medication phenytoin (Dilantin) and the antibiotic amoxicillin.
• Family history. This condition sometimes runs in families.

It's possible to have the antibodies associated with antiphospholipid syndrome without developing signs or symptoms. However, having these antibodies increases your risk of developing blood clots, particularly if you:

• Become pregnant
• Are immobile for a time, such as being on bed rest or sitting during a long flight
• Have surgery
• Smoke cigarettes
• Take oral contraceptives or estrogen therapy for menopause
• Have high cholesterol and triglycerides levels

Depending on which organ is affected by a blood clot and how severe the obstruction of blood flow to that organ is, untreated antiphospholipid syndrome can lead to permanent organ damage or death. Complications include:

• Kidney failure. This can result from decreased blood flow to your kidneys.
• Stroke. Decreased blood flow to a part of your brain can cause a stroke, which can result in permanent neurological damage, such as partial paralysis and loss of speech.
• Cardiovascular problems. A blood clot in your leg can damage the valves in the veins, which keep blood flowing to your heart. This can result in chronic swelling and discoloration in your lower legs. Another possible complication is heart damage.
• Lung problems. These can include high blood pressure in your lungs and pulmonary embolism.
• Pregnancy complications. These can include miscarriages, stillbirths, premature delivery, slow fetal growth and dangerously high blood pressure during pregnancy (preeclampsia).

Rarely, a person can have repeated clotting events in a short time, leading to progressive damage in multiple organs.

If you've had episodes of blood clots or pregnancy loss that aren't explained by known health conditions, your doctor can schedule blood tests to check for abnormal clotting and for the presence of antibodies to phospholipids.

To confirm a diagnosis of antiphospholipid syndrome, the antibodies must appear in your blood at least twice, in tests conducted 12 or more weeks apart.

You can have antiphospholipid antibodies and never develop any signs or symptoms. A diagnosis of antiphospholipid syndrome is made only when these antibodies cause health problems.

If you have blood clots, standard initial treatment involves a combination of blood-thinning medications. The most common are heparin and warfarin (Coumadin, Jantoven). Heparin is fast-acting and delivered via injections. Warfarin comes in pill form and takes several days to take effect. Aspirin is also a blood thinner.

When you're taking blood thinners, you have an increased risk of bleeding episodes. Your doctor will monitor your dosage with blood tests to be sure your blood is capable of clotting enough to stop the bleeding of a cut or the bleeding under the skin from a bruise.

Depending on your treatment plan for antiphospholipid syndrome, there are additional steps you can take to protect your health. If you take blood-thinning medications, take extra care to keep from injuring yourself and to avoid bleeding.

• Avoid contact sports or other activities that could cause bruising or injury or cause you to fall.
• Use a soft toothbrush and waxed floss.
• Shave with an electric razor.
• Take extra care when using knives, scissors and other sharp tools.

Food and dietary supplements

Certain foods and medications may affect how well your blood thinners work. Ask your doctor for guidance about:

• Safe dietary choices. Vitamin K can lessen the effectiveness of warfarin, but not other blood-thinners. You may need to avoid eating large amounts of vitamin K-rich foods such as avocado, broccoli, Brussels sprouts, cabbage, leafy greens and garbanzo beans. Cranberry juice and alcohol can increase warfarin's blood-thinning effect. Ask your doctor if you need to limit or avoid these drinks.
• Safe medications and dietary supplements. Certain medications, vitamins and herbal products can interact dangerously with warfarin. These include some over-the-counter pain relievers, cold medicines, stomach remedies or multivitamins, as well as garlic, ginkgo and green tea products.

In most cases, complications of antiphospholipid syndrome — such as DVT, stroke or pregnancy loss — will prompt you to seek medical care. Depending on your complication, you'll likely see a specialist in vascular disease, obstetrics or hematology.

Here's some information to help you get ready for your appointment.

What you can do

Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance. Make a list of:

• Your signs or symptoms and when they began.
• Write down key personal information, including any major recent events or changes in your life.
• Key medical information, including other conditions or infections you have and family medical history, especially close relatives who've had antiphospholipid syndrome.
• All medications, vitamins and other supplements you take, including doses.
• Questions to ask your doctor.

Take a family member or friend along, if possible, to help you remember the information you get.

For antiphospholipid syndrome, some questions to ask your doctor include:

• What's the most likely cause of my symptoms?
• What tests do I need?
• What treatment do you recommend?
• How will you determine whether my treatment is working?
• Does this condition increase my risk of any other medical problems?
• Does this condition increase my risk of health problems during pregnancy? Are there treatments to reduce that risk?
• Are there brochures or other printed material that I can have? What websites do you recommend?

Don't hesitate to ask other questions, as well.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, including:

• Do you have a history of stroke or blood clots?
• Do you have a history of pregnancy complications, such as high blood pressure, miscarriage or stillbirth?
• Do you have lupus or another autoimmune disorder?
• Have you ever been tested for sexually transmitted infections or chronic viral diseases, such as hepatitis?
• Do you have frequent headaches?
• Have you noticed a red, net-like rash on your wrists or knees?
• Do you smoke?