Essential Thrombocythemia: Signs, Diagnosis and Treatment

Bone marrow disorder

Bone marrow, light micrograph. Credit: Science Photo Library - Steve Gschmeissner / Getty Images

Essential thrombocythemia is a rare disorder in which the body's bone marrow produces too many blood platelet-forming cells (megakaryocytes). ET is part of a category of diseases known as myeloproliferative disorders (MPD). 

Platelets stick together, causing blood to clot and stop bleeding. A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. In essential thrombocythemia, excess platelets may function abnormally and not perform properly and can result in abnormal clotting or bleeding.

What causes essential thrombocythemia to occur is not yet known. However, about 80 percent of people with ET have an acquired gene mutation that contributes to the disease. 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.

Symptoms of Essential Thrombocythemia

Patients with essential thrombocythemia are often first diagnosed after they develop a blood clot. In people with essential thrombocythemia, clots often occur in the brain, hands and feet. Symptoms related to clot formation in these areas include:

  • Headache
  • Dizziness or lightheadedness
  • Chest pain
  • Weakness
  • Fainting
  • Temporary vision changes
  • Numbness or tingling of the hands and feet
  • Redness, throbbing and burning pain in the hands and feet (erythromelalgia)
  • Mildly enlarged spleen

    Less often, patients with essential thrombocythemia can experience bleeding. This may cause nosebleeds, bruising, bleeding from the mouth or gums, and/or blood in the stool. 

    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).

     If a blood clot occurs in the arteries that supply the brain, it may cause a transient ischemic attack (TIA), or mini-stroke. Signs and symptoms of a TIA are similar to those of other strokes, and include:

    • Weakness or numbness of the face, arm or leg, usually on one side of your body
    • Difficulty speaking or understanding speech (aphasia)
    • Blurred, double or decreased vision

    Diagnosing Essential Thrombocythemia

    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.

    Essential Thrombocythemia Treatment

    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 an 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, they may be at higher risk for stroke, heart attack, or other serious complications.

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

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