Conditions & Treatments


Thrombocythemia is a myeloproliferative disorder. It is characterized by the production of too many platelets in the bone marrow.


What is thrombocythemia?

Thrombocythemia, also called primary or essential thrombocythemia, is a myeloproliferative disorder (a type of disease in which the bone marrow makes too many red blood cells, white blood cells, or platelets). It is characterized by the production of too many platelets in the bone marrow. Too many platelets make normal clotting of blood difficult. This can result in too much clotting, or not enough clotting. 

What causes thrombocythemia?

There may be no single cause for thrombocythemia. It is believed to be caused by mutations to megakaryocytes, the platelet-making cells in the bone marrow.

What are the symptoms of thrombocythemia?

The following are the most common symptoms of thrombocythemia. However, each individual may experience symptoms differently. Symptoms may include:

  • Blood clots in arteries and veins, commonly in the hands, feet, and brain 

  • Bleeding

  • Bruising easily

  • Bleeding from the nose, gums, and gastrointestinal tract

  • Bloody stools

  • Hemorrhaging after injury or surgery

  • Weakness

  • Headache and dizziness 

  • Enlarged lymph nodes

The symptoms of thrombocythemia may resemble other blood disorders or medical problems. Always consult your doctor for a diagnosis.

How is thrombocythemia diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for thrombocythemia may include blood tests to measure blood counts, and a blood smear to further assess your platelets. Excluding other causes of reactive thrombocytosis as well as other myeloproliferative disorders is important in the workup. Bone marrow biopsy (the marrow may be removed by aspiration or a needle biopsy under local anesthesia) may also be necessary.

Treatment for thrombocythemia

Specific treatment for thrombocythemia will be determined by your doctor based on:

  • Your age, overall health, and medical history

  • Extent of the disease

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference

Treatment may include:

  • Chemotherapy. This is most often administered with hydroxyurea, an oral chemotherapy drug, or interferon alpha. 

  • Plateletpheresis. This is a procedure to remove extra platelets from the blood.

Treatment Programs

Massachusetts General Hospital understands that a variety of factors influence patients' health care decisions. That's just one reason why we're dedicated to ensuring patients understand their diagnosis and treatment options. Because a single option might not serve all patients, we offer a wide range of coordinated treatments and related services across the hospital. Patients should consult with their primary care doctor or other qualified health care provider for medical advice and diagnosis information.

Select a treatment program for more information:


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