Diseases & Conditions


Thrombocythemia, Essential

Synonyms of Thrombocythemia, Essential
  • Essential Hemorrhagic Thrombocythemia
  • Essential Thrombocytosis
  • ET
  • Idiopathic Thrombocythemia
  • Primary Thrombocythemia

Disorder Subdivisions

    General Discussion
    Essential thrombocythemia (ET) is one of four rare, myeloproliferative disorders (MPDs). Myeloproliferative means uncontrolled production of cells by the bone marrow. Each of the four myeloproliferative disorders is characterized by over-production of a different, but essential, type of blood cell resulting in a high concentration of these cells in the blood.

    Essential thrombocythemia is characterized by overproduction of the precursor cells to blood platelets (megakaryocytes) which, in turn, leads to a vastly increased number of platelets in the blood. Platelets are specialized cells in blood essential for the normal process of clotting. In addition to over-production of platelets, other symptoms and signs of ET may include an enlarged spleen (splenomegaly); bleeding from the gut, gums and/or nose (hemorrhaging); and constricted or blocked arteries (thrombosis).

    As many as two-thirds of patients are without symptoms (asymptomatic) upon initial examination. Most patients present with symptoms related to small or large vessel thrombosis or minor bleeding. Presentation with a major bleeding episode is very unusual. Clots may occur in the small arteries of the toes and fingers, leading to pain, warmth, tissue death (gangrene) and/or classic erythromelalgia. Erythromelalgia refers to a syndrome of redness and burning pain in the extremities. The incidence of the thrombotic and bleeding episodes is minimized, but not eliminated, with reduction of the platelet count to normal.

    In some instances, this chronic disorder may be progressive, evolving in relatively rare cases into acute leukemia or myelofibrosis.

    The three other myeloproliferative disorders are:

    Polycythemia vera, in which blood contains abnormally high concentrations of red blood cells (erythrocytes).

    Chronic myelogenous leukemia, which is characterized by abnormally high concentrations of white blood cells (neutrophils) or their precursor cells, granulocytes.

    Agnogenic myeloid metaplasia, in which red blood cells have the shape of a teardrop rather than a disc. In this disorder, something goes wrong with the marrow microenvironment that affects the structure of the red blood cell.

    These blood cells all arise from a common ancestor, the stem cell, which in its undifferentiated form can become a red blood cell, a white blood cell, or a platelet.

    The term secondary thrombocythemia is used to describe the problems involving persistent, high blood platelet counts associated with some underlying condition such as malignancy, infection, inflammatory disease, or iron deficiency.

    Organizations related to Thrombocythemia, Essential
    • CMPD Education Foundation
      PO Box 4758
      Scottsdale AZ 85261
      Phone #: 480-443-1975
      800 #: N/A
      e-mail: [email protected]
      Home page: http://www.mpdinfo.org
    • Madisons Foundation
      PO Box 241956
      Los Angeles CA 90024
      Phone #: 310-264-0826
      800 #: N/A
      e-mail: geti[email protected]
      Home page: http://www.madisonsfoundation.org
    • Myeloproliferative Disease Support and Free Daily Email Digest
      2011 Flagler Ave.
      Key West FL 33040
      Phone #: 305-295-4444
      800 #: N/A
      e-mail: [email protected] or [email protected]
      Home page: http://www.MPDSUPPORT.ORG
    • Myeloproliferative Mailing List (MPD-SUPPORT-L)
      3706 North Roosevelt Blvd.
      Key West FL 44030
      Phone #: 305-295-4444
      800 #: --
      e-mail: [email protected]
      Home page: http://www.mpdsupport.org
    • NIH/Hematology Branch, National Heart, Lung and Blood Institute (NHLBI)
      10 Center Dr, Building 10-CRC
      Bethesda MD 20892-1202
      Phone #: 301-402-0764
      800 #: --
      e-mail: [email protected]
      Home page: http://dir.nhlbi.nih.gov/labs/hb/index.asp?
    • NIH/National Heart, Lung and Blood Institute Information Center
      P.O. Box 30105
      Bethesda MD 20824-0105
      Phone #: 301-592-8573
      800 #: --
      e-mail: [email protected]
      Home page: N/A
    • Platelet Disorder Support Association
      133 Rollins Avenue
      Rockville MD 20852
      Phone #: 301-770-6636
      800 #: 877-528-3538
      e-mail: [email protected]
      Home page: http://www.pdsa.org

    For a Complete Report

    This is an abstract of a report from the National Organization for Rare Disorders, Inc. ? (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html