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Essential Thrombocythemia

Bone marrow disorder


Updated June 15, 2014

A person with essential thrombocythemia (ET) has an excess amount of platelets in the blood due to a disorder of the bone marrow. A change in the bone marrow stem cell DNA causes the overproduction of platelet-forming cells in the bone marrow. What causes essential thrombocythemia to occur is not yet known. ET is one of the myeloproliferative disorders (MPD).

There are an estimated 0.1 to 2.4 new cases of essential thrombocythemia per 100,000 people per year. ET may occur at any age but tends to be more common in adults. It affects both women and men of all ethnic backgrounds.

Many people with essential thrombocythemia have no symptoms. Others may have symptoms such as:

  • skin problems such as redness, burning, or itching
  • pain in the feet and hands
  • a mildly enlarged spleen
  • headache, dizziness, weight loss
  • abnormal bleeding (rarely)
  • pregnancy complications
  • abnormal blood clotting (most common problem)

If a blood clot forms it may block blood flow to a part of the body. This may cause serious problems such as stroke (a blood clot in the brain) or heart attack (a blood clot in the heart). People who smoke or drink alcohol increase their risk of developing a blood clot.

If an individual has no symptoms, essential thrombocythemia may be diagnosed from a blood test (platelet count) during a routine physical examination. An abnormally high number of platelets will be detected in the blood. The bone marrow may also be examined for the presence of excess platelets, and the spleen will be examined to see if it is enlarged. Other tests may be done to look for other disorders which may also cause a high number of platelets in the blood.

Treatment depends on the level of platelets in the blood and the risk of clotting or bleeding complications. Plateletpheresis (removing platelets from the blood) may be used as an emergency treatment to quickly reduce an extremely high platelet level. Longer-term treatment may be observation of the individual's status through regular doctor visits if the risk for blood clots is low. Those with higher risk may be treated with medications such as hydroxyurea, anagrelide, or interferon alpha.

Individuals with essential thrombocythemia usually have a normal lifespan with proper medical treatment. However, if a stroke, heart attack, or other serious complication occurs, the individual may have disability.

- The Leukemia & Lymphoma Society. Essential or Primary Thrombocythemia
- Arizona Telemedicine Program. Myeloproliferative Disorders

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