THROMBOCYTOPENIAS

Pathogenesis, differential diagnostics and treatment strategies of different types of thrombocytopenias are reviewed. Two major mechanisms responsible for development thrombocytopenia might be distinguished – decreased production and increased consumption of platelets. Decline of platelet production due to the depression of megakaryocytes (productive thrombocytopenia) is usually associated with aplastic anemia, different forms of leukemia and myelodysplasia, or cytostatic therapy. Increased consumption might be induced by auto- and/or alloantibodies which bind to platelets and stimulate their rapid removal by the reticuloendothelial system of spleen and liver (idiopathic thrombocytopeniс purpura, drug-induced thrombocytopenia, neonatal alloimmune thrombocytopenic purpura and other forms of immune
thrombocytopenia). Enhanced consumption of platelets due to the intravascular thrombosis leads to the thrombocytopenia (consumptive nonimmune thrombocytopenia) in disseminated intravascular coagulation syndrome, thrombotic thrombocytopenic purpura and haemolytic uremic syndrome. Hereditary forms of thrombocytopenia are caused by congenital defects of platelet production and/or maturation and anomalies of von Willebrand factor. Many of them are also associated with the impaired platelet morphology and function. Defective platelet production is considered as a cause of low platelet count in the majority of hereditary thrombocytopenias (pure familial thrombocytopenia. TAR syndrome, and others) but in some of them the increased consumption has been detected or proposed (Wiscott-Aldrich syndrome, platelet type and type IIb von Willebrand disease, Bernard-Soulier syndrome). Laboratory methods used for the differential diagnostics of thrombocytopenias include: determination of platelet count by automatic counting and microscopy, analysis of megakaryocytes in the bone marrow, investigation of platelet morphology and function, detection of platelet autoantibodies and analysis of target antigens, determination of platelet life span and turnover. Different strategies (among them platelet transfusion, immunosuppressive and cytostatic therapy, antithrombotic therapy, splenectomy and others) are  recommended for the treatment of productive, consumptive (immune and nonimmune
forms) and hereditary thrombocytopenias.

thrombocytopenias, platelets, megakaryocytes, haemorrhagic syndrome, idiopathic thrombocytopeniс purpura, autoantibodies, platelet antigens

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