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Essential Thrombocythemia

Essential thrombocythemia (ET) is a chronic blood malignancy characterized by an abnormally high number of platelets in the blood. The increase in platelets can cause blood vessel blockages and bleeding, and in late stages can progress to myelofibrosis (fibrous tissue builds up in the bone marrow) or acute leukemia. Essential thrombocythemia is one of a group of rare blood cancers called myeloproliferative neoplasms (MPNs) that develop due to an acquired gene mutation in the bone marrow stem cells.


  • JAK2 (V617F) gene mutations occur in about 60 percent of essential thrombocythemia patients.
  • Calreticulin (CALR) mutations occur in approximately 25 percent of patients and MPL mutations occur in approximately 10 percent of patients. Four to five percent are “triple negative.”
  • About 2.2 in every 100,000 people are diagnosed with essential thrombocythemia annually. 

Risk Factors

The exact causes of the acquired genetic mutation seen essential thrombocythemia are not yet known. Other risk factors may include:

  • Gender: Women are one and a half times more likely to develop essential thrombocythemia than men.
  • Age: A majority of patients diagnosed with essential thrombocythemia are older than 60. Approximately one in five patients is under age 40.
  • Gene Mutations: The JAK2 gene is most often mutated at V617F, followed in frequency by CALR and MPL mutations.


Many patients with essential thrombocythemia do not have symptoms when they are diagnosed. Diagnoses often occur during a routine exam or blood test. However, if a patient experiences symptoms, they may include the following:

  • Fatigue
  • Headache or silent migraines
  • Visual or hearing disturbances
  • Dizziness
  • Coldness, blueness, or pain in the fingers or toes
  • Burning, redness, throbbing, and pain in the hands and feet
  • Unexplained pain
  • Numbness and tingling
  • Stroke
  • Transient ischemic attack (TIA)
  • Heart attack
  • Deep vein thrombosis
  • Blood clot in lung
  • Easy bruising
  • Slurred speech
  • Numbness or weakness on one side of the body
  • Abnormal bleeding such as nosebleeds, heavy menses, blood in urine, or gastrointestinal bleeding
  • Low-grade fever
  • Itching
  • Sweating
  • Discomfort in upper left side of abdomen, caused by an enlarged spleen, occasionally with loss of appetite


Essential thrombocythemia cannot be prevented. Research is underway to learn more about how the disease develops.


Essential thrombocythemia patients who do not experience symptoms, are younger, and without cardiovascular comorbidities may not need active treatment, other than monitoring. However, if symptoms are present, treatment options include low-dose aspirin or medications such as hydroxyurea, anagrelide, and interferon. Clinical trials can also be an important treatment option, with ruxolitinib showing promise.

Sources: Leukemia and Lymphoma Society, MPN Research Foundation, and National Cancer Institute