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Essential Thrombocythemia

(Primary Thrombocythemia)


Jane Liesveld

, MD, James P. Wilmot Cancer Institute, University of Rochester Medical Center

Reviewed/Revised Jul 2022 | Modified Sep 2022
  • The hands and feet may burn, turn red, and tingle, and the fingertips may feel cold.

  • Blood tests usually provide a diagnosis, but sometimes a bone marrow biopsy is needed.

  • Treatments that suppress symptoms and decrease platelet production are given.

Platelets Platelets The main components of blood include Plasma Red blood cells White blood cells Platelets read more Platelets (thrombocytes) are cell-like particles in the blood that help the body form blood clots. Platelets are normally produced in the bone marrow by cells called megakaryocytes. In thrombocythemia, megakaryocytes increase in number and produce too many platelets. Thrombocythemia can be

Essential thrombocythemia usually occurs in people over age 50. Sometimes younger patients, especially young women are affected.

Essential thrombocythemia is considered a myeloproliferative neoplasm, in which certain blood-producing cells Formation of Blood Cells Red blood cells, most white blood cells, and platelets are produced in the bone marrow, the soft fatty tissue inside bone cavities. Two types of white blood cells, T and B cells ( lymphocytes)... read more in the bone marrow develop and reproduce excessively. The cause of is a genetic mutation usually in the Janus kinase 2 (JAK2), thrombopoietin receptor (MPL), or calreticulin (CALR) genes. The JAK2 gene mutation causes increased activity of the JAK2 enzyme, a protein that causes excess cell production.


Serious complications are rare but can be life-threatening.

Blood clots may form in almost any blood vessel. Blood clots in large blood vessels may affect the legs (deep vein thrombosis), brain (stroke), heart (heart attack), or lungs (pulmonary embolism). Blood clots in tiny blood vessels can affect the eyes, brain, and skin.

Excessive bleeding also can occur. Although an increased number of platelets might be thought to always cause excessive blood clotting, a very high number of platelets can actually cause bleeding by affecting other parts of the body's clotting system.

Symptoms of Essential Thrombocythemia

Primary thrombocythemia may or may not cause symptoms. When symptoms occur, they are due to the blockage of blood vessels by blood clots and may include

  • Redness and warmth of the hands and feet, often with burning pain (erythromelalgia)

  • Tingling and other abnormal sensations in the fingertips, hands, and feet

  • Chest pain

  • Loss of vision or seeing spots

  • Headaches

  • Weakness

  • Dizziness

  • Bleeding, usually mild (such as nosebleeds, easy bruising, slight oozing from the gums, or bleeding in the digestive tract)

The spleen may enlarge but this is rare at time of diagnosis and more common in females.

Diagnosis of Essential Thrombocythemia

  • Blood tests

  • Genetic tests

  • Sometimes bone marrow biopsy

Doctors make a diagnosis of primary thrombocythemia on the basis of the symptoms and after finding increased platelets on a blood count. Other blood tests, including genetic tests for the JAK2, CALR, or MPL mutations are done. In addition, microscopic examination of the blood may reveal abnormally large platelets, clumps of platelets, and fragments of megakaryocytes.

Treatment of Essential Thrombocythemia

  • Aspirin to relieve symptoms

  • Drugs to decrease platelet count

Aspirin, which makes platelets less sticky and impairs clotting, may be given in small doses to help relieve mild symptoms such as redness and warmth of hands and feet, and headache, but people with significant bleeding should not take aspirin.

Thrombocythemia may also require treatment with a drug that decreases platelet production. Such drugs include hydroxyurea, anagrelide, interferon-alpha, and ruxolitinib.

Treatment with one of these drugs is typically started when clotting or bleeding complications develop and not just based on the platelet count.

If drug treatment does not slow platelet production quickly enough, it may be combined with or replaced by plateletpheresis Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more , a procedure reserved for emergency situations. In this procedure, blood is withdrawn, platelets are removed from it, and the platelet-depleted blood is returned to the person. However, plateletpheresis is inefficient and only a temporary solution.

More Information

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

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