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Abnormal Blood Clotting with Lupus

Reviewed by: HU Medical Review Board | Last reviewed: January 2020

Abnormal blood clotting is one of the most interesting and most common symptoms of lupus. It can cause either extreme of too much clotting or too little. Abnormal blood clotting can be present even when a person’s lupus is otherwise under control.1

Any type of abnormal blood clotting can be dangerous and must be treated as quickly as possible. This is why your doctor will monitor your blood work closely during every appointment by ordering a complete blood count (CBC).

You may need to see a hematologist, a doctor who specializes in blood disorders if you develop abnormal blood clotting related to lupus.

Why does lupus cause abnormal blood clotting?

Abnormal blood clotting happens in people with lupus because the disease causes the body to produce too many antibodies. Antibodies are proteins that circulate in the blood and attack things it thinks are alien, such as bacteria and viruses. In people with lupus, these antibodies attack healthy cells.2

There are many different types of antibodies, and each has a specific job. Thirty percent to 50 percent of people with lupus possess antiphospholipid antibodies or antibodies that bind with phospholipids. Having antiphospholipid antibodies makes it much more likely that you will develop blood clots compared to someone with normal blood. These antibodies are also associated with pregnancy complications and miscarriages. When someone has complications related to these antibodies they may be diagnosed with antiphospholipid antibody syndrome.

On the other hand, lupus may also cause thrombocytopenia or too few platelets in the blood. Between 25 percent and 50 percent of people with lupus develop mild thrombocytopenia. This can lead to excessive bleeding.3

In people with lupus, thrombocytopenia may be the result of:4

  • Antibodies mistakenly attacking healthy platelets
  • An enlarged spleen that traps platelets rather than letting them circulate in the blood
  • Certain drugs used to treat other lupus symptoms

Complications of blood clotting

Blood that clots too easily can lead to a variety of serious complications, including:1,3

  • Strokes (blood clot in the brain)
  • Pulmonary embolism (blood clot in the lungs)
  • Deep vein thrombosis (blood clot in the legs)
  • Libman-Sacks endocarditis (blood clot in a heart valve)
  • Heart attack
  • Seizures
  • Pregnancy complications including miscarriage

Blood that does not clot fast enough (thrombocytopenia) can cause:1,3,4

  • Skin conditions such as livedo, petechiae, or easy bruising (purpura)
  • Enlarged spleen
  • Jaundice
  • Uncontrolled bleeding after a cut or surgery
  • Internal bleeding
  • Blood in the urine or stool

Abnormal blood clotting treatments

Many options exist for treating abnormal blood clotting. In people whose blood clots too easily, anticoagulants may be prescribed. Aspirin may be recommended. Hydroxychloroquine which is used to treat lupus also may reduce the risk of blood clots in some people.

Thrombocytopenia may be caused or made worse by certain medications used to treat other lupus symptoms, so those may be reduced or eliminated. Thrombocytopenia may also be affected by vitamin B12 and folate levels, so your doctor may suggest eating foods rich in these nutrients.4

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