Pathophysiological aspects of Platelet-Mediated Thrombosis and Bleeding in Essential Thrombocythemia:

textabstractThrombocytosis, i.e. an elevation of the platelet count, is a common finding in clinical practice. In general, patients with thrombocytosis are distinguished into two main categories, primarily based on the cause underlying the increased platelet count. The term "reactive thrombocytosis (RT)" has commonly been applied to the condition of an increased platelet count after a period of bone marrow suppression associated with chronic or acute inflammation or infections, malignant diseases, hemorrhage, iron deficiency, or after splenectomy. In contrast, the condition in those patients in whom there is a clonal proliferative drive to enhanced platelet production is termed "thrombocythemia". Thrombocythemia may occur in its primary form (also known as essential thrombocythemia) or may accompany any of the other myeloproliferative disorders polycythemia vera (PV), myeloid metaplasia with myelofibrosis (MMM), chronic myeloid leukemia (CML) as well as myelodysplastic syndromes. The clinical course, treatment and prognosis vary considerably for patients with reactive thrombocytosis, myeloproliferative disorders and myelodysplastic syndromes. Therefore, a thorough analysis of the cause for the increased platelet count is warranted. This thesis will deal with essential thrombocythemia (ET), a myeloproliferative disorder characterized by a sustained elevation of the platelet count and a paradoxical predisposition to both thrombotic and bleeding complications