| Popis: |
Essential thrombocytosis (ET) is clonal chronic myeloproliferative disorder which originates from abnormality of a multipotent hematopoietic stem cell.It is characterized by an increased platelet count, megakaryocytic hyperplasia and by hemorrhagic or thrombotic tendency. Symptoms and signs may include weakness, headaches, paresthesias, bleeding, splenomegaly, and digital ischemia. ET patients showed equal or slightly shorter survival than age- and sex-matched healthy population. Major causes of death were thrombotic and hemorrhagic complications or malignant progression due to both the natural history of the disease and, possibly, the use of chemotherapeutic agents.Diagnostic criteria for essential thrombocythemia were proposed in 2005 by the PVSG and demand diagnosis of exclusion.Myelosuppressive therapy to lower the platelet count usually consists of hydroxyurea, interferon alpha or anagrelide. Hydroxyurea is the most commonly used treatment, because of its efficacy, low cost and rare acute toxicity. Interferon alpha is a biological response modifier. It is not known to be teratogenic and does not cross the placenta, and is often the treatment of choice during pregnancy. Anagrelid suppresses bone marrow megakaryocytes by interfering with the maturation process and decreasing platelet production without affecting other blood cell lines. Low-dose aspirin may be used to control microvascular symptoms.Recommendations for management of patients with essential thrombocythemia were given by ASH. From a treatment standpoint, hydroxyurea is now confirmed to be the drug of choice for high-risk patients with essential thrombocythemia. Interferon alpha and anagrelide are reasonable second-line agents. Low-risk patients should receive low-dose aspirin alone. For the intermediate-risk patients, a consensus could not be reached on a recommendation for platelet-lowering treatment. |
