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Primary thrombocythemia

Primary thrombocythemia is a condition in which the bone marrow produces too many platelets. Platelets are a part of the blood that aids in blood clotting.

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Primary thrombocythemia is caused by the overproduction of platelets. If untreated, this condition gets worse over time. Because these platelets do not work normally, bleeding is a common problem.

The disease is part of a group of conditions known as myeloproliferative disorders. Others include:

This disorder is most common in middle aged people. It can also be seen in younger people, especially women under age 40.


Symptoms may include any of the following:

  • Bleeding from the gastrointestinal tract, respiratory system, urinary tract, or skin
  • Bleeding from the gums
  • Bleeding (prolonged) from surgical procedures or tooth removal
  • Dizziness and headaches
  • Easy bruising and nosebleeds (epistaxis)
  • Numbness of the hands or feet
  • Ulcers on the fingers or toes

The condition can even cause strokes in some people.

Exams and Tests

Most of the time, this condition is found through blood tests done for other conditions before symptoms appear.

Your health care provider may notice an enlarged liver or spleen on physical examination. You may also have abnormal blood flow in the toes or feet that causes skin damage in these areas.

Other tests may include:

  • Bone marrow biopsy
  • CBC
  • Genetic tests (to look for a change in the JAK2 gene)
  • Uric acid level


If you have life-threatening complications, you may have a treatment called platelet pheresis. It quickly reduces platelets in the blood.

Long-term, medicines are used to decrease the platelet count to avoid complications. The most common medicines used include hydroxyurea, interferon-alpha, or anagrelide. In some people with a JAK2 mutation, specific inhibitors of the JAK2 protein may be used.

In people who are at a high risk for clotting, aspirin at a low dose (81 to 100 mg per day) decreases clotting episodes. People who may benefit from this treatment include older people and people with very high platelet levels or who have had past clotting episodes.

Many people do not need any treatment, but they must be followed closely by their provider.

Outlook (Prognosis)

While outcomes can vary, most people can go for long periods without complications and have a normal lifespan. In a small number of people, complications from bleeding and blood clots can cause serious problems.

In rare cases, the disease can change into acute leukemia or myelofibrosis.

Possible Complications

Complications may include:

When to Contact a Medical Professional

Call your health care provider if:

Alternative Names

Essential thrombocythemia; Essential thrombocytosis



Hoffman R, Kremyanskaya M, Najfeld V, et al. Essential thrombocythemia. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, Anastasi J, eds.Hematology: Basic Principles and Practice

Tefferi A. Polycythemia vera, essential thrombocytoemia, and primary myelofibrosis. In: Goldman L, Schafer AI, eds.Goldman's Cecil Medicine

Update Date 2/13/2015

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