Antiphospholipid syndrome (APS)




Antiphospholipid syndrome (APS), also known as Hughes syndrome, is a disorder of the body's defense system (immune system) characterized by episodes of thrombosis (formation of clots inside the blood vessels), repeated miscarriages (loss of blood fetus) and a low amount of platelets in the blood (thrombocytopenia).

People with APS can develop:

  • deep vein thrombosis, blood clots in the lower extremities
  • arterial thrombosis, which can cause stroke or heart attack
  • brain clots, with consequent problems of balance, mobility, vision, speech and memory

APS is an autoimmune disease. This means that the immune system, which normally protects the body from infections and diseases, attacks its own healthy tissues by producing abnormal antibodies, called antiphospholipid antibodies. It is believed that they interfere with clotting causing thrombosis in every part of the body.

It is not known what causes the immune system to produce autoantibodies but, as with other autoimmune diseases, genetic, hormonal and environmental factors are thought to play a role.

Two forms of APS are known:

  • Primary APS, which occurs in individuals with no other apparent autoimmune disorders
  • Secondary APS, which appears in association with another autoimmune disease, mostly systemic lupus erythematosus (SLE)

APS can affect people of all ages, including children and babies; however, most sufferers are between the ages of 20 and 50, and it occurs in three to five times more women than men.

Although there is no definitive cure, the risk of forming blood clots can be greatly reduced if APS is correctly ascertained (diagnosed) and treated with anticoagulant or antiplatelet drugs.

These are medicines that reduce the formation of unnecessary clots by maintaining the ability of the blood to clot in the event of an injury.

Furthermore, the use of these drugs can increase the chance of carrying a pregnancy by up to 80%.

Most sufferers respond well to treatment and can lead a normal and healthy life. However, a small number of people, despite treatment, continue to form clots.

In very rare cases, they can suddenly form throughout the body, resulting in failure of multiple organs. These cases are known as catastrophic antiphospholipid antibody syndrome (CAPS) and require immediate, emergency treatment in the hospital with high doses of anticoagulants.



In antiphospholipid syndrome (APS), the body's defense system (immune system) produces abnormal antibodies that make the blood thicker than normal, increasing the likelihood that blood clots may form and, consequently, health problems such as:

  • hypertension (high blood pressure)
  • deep vein thrombosis (DVT)
  • stroke or transient ischemic attack (TIA) or mini-stroke
  • heart attack
  • pulmonary embolism (clot that creates a blockage in one of the blood vessels in the lungs)
  • miscarriages and other pregnancy complications such as premature birth and increased blood pressure (preeclampsia)

APS sufferers may also have one of the following disorders (symptoms):

  • problems with balance and movement
  • poor eyesight, such as double vision (diplopia)
  • speech and memory problems
  • tingling or needling sensation (paraesthesia) in the arms or legs
  • fatigue (extreme fatigue)
  • repeated headaches or migraines
  • bleeding due to a decrease (thrombocytopenia) in the blood cells necessary for normal clotting (platelets)

Problems in pregnancy

Untreated women with APS have a much higher risk of having complications such as:

  • repeated miscarriages (three or more), in the early stages of pregnancy (in the first 10 weeks of pregnancy)
  • late miscarriages (one or more, after the first 10 weeks of pregnancy)
  • premature birth, at or before the 34th week of pregnancy, caused by preeclampsia (blood hypertension in pregnancy)

Livedo reticularis

The reticular livedo it is a condition caused by small blood clots that develop inside the blood vessels of the skin.

The skin takes on a red or blue patchy appearance, and ulcers (sores) and lumps (bumps) can sometimes occur. These complaints (symptoms) are often more severe in the cold season.

Superficial thrombophlebitis

Superficial thrombophlebitis is "inflammation of the veins just below the skin of the lower limbs. The symptoms (symptoms) are similar to those of deep vein thrombosis, but are less severe and include:

  • swelling
  • redness and soreness along the affected vein
  • body temperature of 38 ° C or higher (fever)

They usually resolve within two to six weeks.

Emergency intervention is recommended in the presence of some serious signs and complaints:

  • signs and disorders related to stroke such as, for example, sudden numbness, weakness or paralysis of the face, arm or leg; sudden difficulties in speaking and understanding language, visual disturbances, severe headache and dizziness
  • signs and disorders associated with pulmonary embolism such as a sudden shortness of breath, chest pain and cough with blood-streaked sputum
  • signs of deep vein thrombosis such as swelling or pain in the legs
  • unexplained bleeding from the nose or gums; unusually heavy menstrual cycle; vomit that is bright red or that looks like coffee beans; black or bright red stools; unexplained abdominal pain


Antiphospholipid syndrome (APS) is caused by the body's defense system (immune system) producing abnormal antibodies, called antiphospholipid antibodies, which attack healthy body tissues.

The cause of the production of these abnormal antibodies is unclear, as it is unclear why many people who have antiphospholipid antibodies do not produce clots.

A combination of genetic and environmental factors is thought to be responsible.

Antiphospholipid antibodies

Antibodies are proteins produced by the immune system, as part of the body's defense system, to fight infections from bacteria and viruses and to prevent their spread.

In APS, the immune system produces abnormal antibodies which, instead of attacking bacteria and viruses, mistakenly attack certain proteins that bind phospholipids, a type of fat found on the surface of blood cells and blood vessels. There are several mechanisms involved:

  • antibodies recognize protein-phospholipid complexes present on the surface of the cells that line the blood vessels (endothelial cells) or on the white blood cells, they bind to them and alter the function of these cells, promoting clotting
  • antibodies bind to protein-phospholipid complexes which are part of the coagulation process (coagulation cascade), alter their properties, ultimately favoring both the formation of the clot and its slower disappearance

Genetic factors

Research into the genetics of APS is still in its infancy, but it appears that genes inherited from parents may play a role in the development of abnormal antiphospholipid antibodies.

APS is not passed down directly from parents to children as in other diseases (such as "haemophilia or sickle cell anemia), however, having a family member with antiphospholipid antibodies increases the likelihood of getting APS.

Studies show that some APS sufferers have a defective gene that plays a role in other autoimmune diseases such as lupus. This may explain why some people develop APS along with other autoimmune diseases.

Environmental factors

It is believed that one or more environmental factors may play a role in "triggering APS:

  • viral infections, such as cytomegalovirus (CMV), parvovirus B19, HIV or hepatitis C
  • bacterial infections, such as that caused byescherichia coli (a bacterium, often associated with food poisoning) or the leptospirosis (an "infection transmitted by some animals)
  • some medications, such as antiepileptics, birth control pills, or hormone replacement therapy (HRT)

Other risk factors seem to be linked to wrong lifestyles:

  • high cholesterol levels in the blood due to an unhealthy diet
  • lack of exercise
  • smoke
  • obesity


It is important to ascertain (diagnose) the presence of antiphospholipid syndrome (APS) to prevent the serious consequences of clot formation.

The assessment of APS is based on the results of specific blood tests, medical evaluation and in the case of thrombotic episodes, recurrent abortions or thrombocytopenia.

If the doctor suspects the presence of APS, he will refer the patient to a haematologist (expert in blood diseases) or rheumatologist (expert in diseases of the immune system).

Blood tests

To ascertain (diagnose) APS it is necessary to carry out specific tests for antiphospholipid antibodies in the blood.

If antiphospholipid antibodies are found during an initial examination, it will be necessary to repeat the test, at least 12 weeks after the first, to confirm their presence.

The diagnosis of APS, therefore, can only be made after obtaining two positive results. The body, in fact, could temporarily produce antiphospholipid antibodies in response to an infection or as an undesirable effect (side effect) of some drugs such as, for example, antibiotics.

In relation to the disorders (symptoms) detected and the state of health of each person, the doctor may prescribe one or more tests to check the presence, or not, of antiphospholipid antibodies and ascertain the APS:

  • anti-cardiolipin antibodies (IgG, IgM and sometimes IgA), are the most common antiphospholipid antibodies
  • lupus anticoagulant test, for the search for antibodies associated with hypercoagulation
  • anti-beta2 glycoprotein I. And test anti-phosphatidylserine they may be requested in conjunction with other antiphospholipid antibodies to provide the physician with additional information

Medical evaluation

If blood tests confirm the presence of antiphospholipid antibodies, the doctor will carefully evaluate the patient's state of health over time to check whether the complaints (symptoms) may be caused by APS.

The disease is generally confirmed in the presence of:

  • one or more episodes of blood clots
  • one or more late abortions, at or after the 10th week of pregnancy
  • one or more premature birthsand, at or before the 34th week of pregnancy
  • three or more early miscarriages, before the 10th week of pregnancy


Treatment of antiphospholipid syndrome (APS) aims to reduce the risk of clot formation.

Doctors prescribe anticoagulant or antiplatelet drugs that work by stopping the process of blood clot formation if not needed.

The treatment plan for APS patients provides for the intake of anticoagulants or antiplatelet drugs every day for life.

If blood tests show the presence of abnormal antiphospholipid antibodies, without the formation of blood clots, it is usually recommended to use a low dose of antiplatelet agents (low-dose aspirin).

In cases where deep vein thrombosis (DVT) or stroke has already occurred, anticoagulants (warfarin and heparin) are recommended:

  • heparin, anticoagulant given as a subcutaneous injection. It can be combined with another blood thinner, warfarin, given in pill form
  • warfarin, after many days of combined therapy with heparin, the doctor may decide whether to continue the treatment with warfarin alone for a very long time
  • aspirinIn some cases, your doctor may recommend the addition of low-dose aspirin

If you are planning to become pregnant, or if you are already pregnant, the plan of treatment will need to be changed by your doctor.

In the event that a blood clot forms, or the symptoms (symptoms) suddenly worsen, you may need injections of an anticoagulant (heparin). They can be administered in the hospital or you can be trained to do them yourself and thus become autonomous.

Side effects of drugs

Side effects of the drugs used for the treatment of APS are rare and generally mild, such as, for example, stomach acid or nausea.

However, there is a risk that the reduced ability of the blood to clot can cause episodes of excessive bleeding (haemorrhages). The signs are:

  • blood in the urine or stool
  • dark stools
  • bruising
  • prolonged nose bleeds (lasting more than 10 minutes)
  • blood in the vomit
  • coughing up blood

If any of these symptoms (symptoms) occur while taking a blood thinner, you should seek immediate medical attention.

Care during pregnancy

Women with antiphospholipid syndrome who intend to have a baby are advised to plan their pregnancy: early treatment, immediately after an attempt to conceive, is more effective and improves the likelihood that the pregnancy will end successfully.

If, on the other hand, it is not planned and the woman realizes that she is pregnant, the treatment may not achieve the purpose of safeguarding the pregnancy.

Treatment consists of taking daily doses of antiplatelet drugs (aspirin) or anticoagulants (heparin), or a combination of both drugs. Warfarin is avoided during this period because it can cause birth defects (teratogenic effect).

Treatment with aspirin and / or heparin is usually started at the beginning of pregnancy and continued up to 1-6 weeks after delivery.

Finally, statins, drugs normally used to lower the amount of cholesterol in the blood, appear to reduce the risk of blood clots and cardiovascular disease in antiphospholipid antibody syndrome.



If left untreated, antiphospholipid syndrome can cause permanent damage and even be life threatening. Complications that can occur include:

  • kidney failure, caused by a decrease in blood flow to the kidneys
  • stroke, caused by decreased blood flow to part of the brain. Can cause permanent neurological damage, such as partial paralysis and loss of speech (aphasia)
  • cardiovascular problems, deep vein thrombosis in the lower limbs can cause chronic venous insufficiency resulting in impaired blood flow to the heart. Another possible complication is heart damage
  • lung problems, high blood pressure in the lungs (pulmonary hypertension) and pulmonary embolism may occur
  • complications during pregnancy, represented by miscarriages, mortality at birth, premature birth and high blood pressure during pregnancy (preeclampsia)
  • catastrophic antiphospholipid syndrome (CAPS), rare but serious complication of antiphospholipid syndrome (APS) which occurs in less than 1% of people with

In people who develop CAPS, blood clots suddenly form throughout the body resulting in failure of multiple organs.

It is not clear what causes this complication but, in one in five cases, it occurs after an "infection, trauma or surgery.

The initial symptoms (symptoms) can be different, depending on which organs were involved:

  • lack of blood supply to the fingertips or toes which take on a dark blue or black color
  • swelling of the ankles, feet or hands
  • increasing difficulty in breathing (dyspnea)
  • abdominal pain
  • blood in the urine
  • mental confusion
  • convulsions
  • coma

Disorders (symptoms) usually develop suddenly, worsen rapidly and require urgent help from an ambulance.

For people with CAPS, immediate admission to an intensive care unit is required. High-dose anticoagulants will be used to stop clot formation.

Mortality is approximately 50% of those affected

Living with

Living with

For people with APS, it is important to take all possible measures to reduce the risk of developing blood clots. Effective lifestyles to achieve this are:

  • not smoking
  • follow a healthy and balanced diet, low in fat and sugar and containing a lot of fruit and vegetables
  • exercise regularly
  • maintaining a healthy body weight and lose weight if you are obese (body mass index over 30)

Estrogen-containing medications such as the combined oral contraceptive pill and hormone replacement therapy should also be avoided. These medicines increase the risk of having a blood clot. Precautions to be taken while taking anticoagulants include:

  • avoid contact sports or other activities that could cause bruising or injury
  • use a soft toothbrush and waxed dental floss
  • shave with an electric razor
  • be especially careful when using knives, scissors or other sharp tools

Certain foods and medications can interact with anticoagulant treatment. You should ask your doctor about:

  • vitamin K, as it may reduce the effectiveness of warfarin. The average daily value of vitamin K for adults is 120 micrograms (mcg) in men and 90 mcg for women. While eating small amounts of foods rich in vitamin K may not be harmful, avoid consuming large quantities of kale, spinach, lettuce, broccoli, Brussels sprouts, parsley, mustard and soy
  • cranberry juice and alcohol, as they can dangerously increase the anticoagulant effect of warfarin. It is advisable to consult your doctor to know if it is necessary to limit or avoid such drinks
  • some medications, vitamins, and herbal products, as they can interact dangerously with warfarin. They include: pain relievers, cold medicines, multivitamins, garlic, ginkgo supplement, and green tea products


NHS. Antiphospholipid syndrome (APS) (English)

Mayo Clinic. Antiphospholipid syndrome (APS) (English)

In-depth link

In-depth link

Tektonidou MG, Andreoli L, Limper M, et al. EULAR recommendations for the management of antiphospholipid syndrome in adults. Annals of the Rheumatic Diseases. 2019; 78: 1296-1304

Tektonidou MG, Andreoli L, Limper M, Tincani A, & Ward M M. Management of thrombotic and obstetric antiphospholipid syndrome: a systematic literature review informing the EULAR recommendations for the management of antiphospholipid syndrome in adults. RMD Open. 2019; 5

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