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Essential thrombocythemia


Essential thrombocythemia (ET) is a disorder of the bone marrow characterized by an overproduction of platelets (thrombocytes). This overproduction of platelets can lead to an increased risk of blood clots (thrombus) and bleeding (hemorrhage). However, with a successful treatment, most patients with ET have a near normal life expectancy.

Diagnosis

Essential thrombocythemia is often diagnosed by chance after a routine blood test. Further analysis as follows:

Blood analysis

  • Permanent increase in thrombocyte count  > 450.000/μl
  • Platelet (thrombocytes) function may be either impaired or normal.

Bone marrow puncture

A bone marrow puncture is required in order to confirm the existence of the disease.

Genetic analysis

Distinct acquired mutations in myeloproliferative diseases may be indicative for underlying afflictions. The Philadelphia chromosome abnormality with its shortened chromosome 22 is associated with chronic myelogenous leukemia. The JAK2 V617F gene mutation may be found in chronic myeloproliferative diseases such as polycythemia vera or essential thrombocythemia. Genetic testing is gaining increasingly widespread support due to its easily obtainable and precise diagnostic parameters that could also minimize the need for further invasive diagnostic procedures.

Ultrasound scan

An ultra sound scan can be used to assess hepatosplenomegaly, which can then provide an indication of how far the disease has progressed.

Treatment

The following medical treatment is available:

  • Anagrelide causes a reduction in the platelet count by inhibiting the maturation of platelets.
  • Hydroxyurea stops stem cell growth altogether.
  • Interferon alpha is a natural substance that influences stem cell growth.

The platelet count can be effectively reduced through the use of anagrelide. As the long-term effects of hydroxyurea still remain unknown, it should not be used to treat younger patients.

In addition to the regular treatments many patients are given small dosages of acetylsalicylic acid (ASA) in order to prevent the formation of blood clots. However, in patients with high platelet counts, the use of ASA is contraindicated as there is a significantly higher risk of bleeding in these cases.

The choice of treatment depends on the risk factors present in each individual patient. Risk factors include:

  • Known thromboembolic complications or severe bleeding
  • Being above the age of 60
  • Thrombocyte count above 1,000,000/µl

A patient is considered high risk if they meet the criteria for just one of the three risk factors listed above. A patient is considered low risk if they do not meet any of the criteria. However, a patient can be considered medium risk if they suffer from high blood pressure, diabetes mellitus, hypercholesterinemia, or if they are a heavy smoker.