[Diagnosis and therapy for patients with essential thrombocythemia. Guidelines of Croatian Cooperative Group for hematologic disorders--KROHEM].

Essential thrombocythemia (ET) is a clonal myeloproliferative neoplasm. Croatian Cooperative Group for hematologic disorders, KROHEM proposes the diagnostic and treatment guidelines for ET. Diagnosis of ET is based on the criteria and classification of World Health Organization (WHO). The level of treatment recommendation is based on the UpToDate (web based medical community database) criteria. For ET diagnosis it is mandatory to show sustained increased number of platelets with typical histomorphological changes of megakaryopoiesis in bone marrow. Secondary thrombocytosis and other chronic myeloproliferative neoplasms have to be excluded. Therapy is based on risk factors for ET. The risk factors are number of platelets, patient's age, and the risk levels for thrombosis and bleeding. Patients with low risk (age < 60 years and platelets < 1000 x 10(9)/L) arw not candidates for therapy. In younger group of patients with platelets between 1000 and 1500 x 10(9)/L or more than 1500 x 10(9)/L treatment with anagrelide or hydroxyurea is recommended respectively. In high risk patients hydroxyurea is the first line treatment. Anagrelide is indicated in these patients in the absence of treatment response. Alpha-interferon is recommended for pregnant women with ET and high platelet counts.