Diagnosing Antiphospholipid Syndrome

NYU Langone doctors are experienced at diagnosing antiphospholipid syndrome, an autoimmune condition in which the body makes antibodies that attack phospholipids—a type of fat found in all cells and their membranes, including blood cells and the lining of blood vessels. Antibodies, a type of protein, usually help to protect the body from infections caused by foreign substances, such as viruses or bacteria. 

Phospholipids are needed for blood clotting, or coagulation. When antibodies attack phospholipids, cells are damaged, causing blood clots to form in the arteries and veins. These can block normal blood flow through the vessels, which raises the risk that a serious condition, such as stroke, may occur. 

Signs and symptoms of antiphospholipid syndrome include cardiovascular problems, such as blood clots in the veins or arteries. Blood clots in the veins often lead to a serious condition called deep vein thrombosis, and clots in the arteries can cause stroke. 

Blood clots that form in the veins most frequently occur in the lower legs. These can break off and travel to the lungs, causing a pulmonary embolism. A pulmonary embolism blocks blood flow to the lungs and decreases the amount of oxygen in the blood, potentially causing lung tissue damage or even sudden death. 

Other conditions associated with antiphospholipid syndrome include: heart valve disease, in which one or more of the heart valves may leak or thicken in a manner that obstructs blood flow; thrombocytopenia, which is a reduction in the number of platelets, a type of blood cell that helps blood to clot; kidney disease; and livedo reticularis, a mottled, purple pattern typically found on the skin of the lower limbs. 

Women who have antiphospholipid syndrome may have multiple miscarriages, miscarriages late in pregnancy, or stillbirths. Babies whose mothers have antiphospholipid syndrome are at higher risk for slowed growth while in the womb, which may lead to premature birth. NYU Langone doctors typically recommend that pregnant women who have antiphospholipid syndrome undergo frequent ultrasound scans during pregnancy to monitor the unborn child's growth.

The presence of antiphospholipid antibodies in the blood does not necessarily indicate that a person has antiphospholipid syndrome. For unknown reasons, the immune system can produce antiphospholipid antibodies but the person never develops signs or symptoms of the disorder.

Although antiphospholipid antibodies may be found in people who have no other health concerns, they are more likely to be present in those who have other autoimmune disorders, such as systemic lupus erythematosus or rheumatoid arthritis. Antiphospholipid syndrome can affect people of any age and is more common in women than men.

To be diagnosed with the condition, you must be found to have antiphospholipid antibodies as well as a history of health problems related to the disorder, such as one or more episodes of thrombosis—a blood clot inside a vessel that obstructs blood flow—or pregnancy-related complications. Early diagnosis is important to prevent further complications from the condition, such as stroke or damage to the blood vessels or internal organs. 

During the diagnostic process, NYU Langone doctors obtain a medical history, perform a physical exam, and order blood tests.

Medical History

Our doctors ask questions about your medical history and want to know if you have been treated for blood clots in the past or any conditions that may cause blood clots, such as vasculitis or diabetes. They also ask women if they’ve had any pregnancy-related complications, such as early recurrent miscarriages or a history of late-term miscarriages or stillbirths.

Physical Exam

Your doctor performs a physical exam to look for any signs of damage to the blood vessels or arteries. This may include swelling in the legs or the presence of livedo reticularis on the skin. They also look for skin ulcers, which are sores on the body, and gangrene, a condition that develops when a lack of blood flow or an infection causes skin tissue to die, most often in the body’s extremities, such as the feet or lower legs.

Blood Tests

The most common way to determine if a person has antiphospholipid syndrome is to conduct a simple blood test, which can detect the presence of antiphospholipid antibodies. Most people undergo at least two blood tests, spaced three months apart, to test for the sustained presence of antiphospholipid antibodies.

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