[Summary of pathophysiology and diagnosis of patients with platelet abnormality]

In hematological disorders, thrombocytopenia is frequently observed, and it is sometimes difficult to diagnose the underlying disease. In this symposium, laboratory tests for platelet abnormality were reviewed. Tests for platelet aggregation were reported to be important for the diagnosis of platelet dysfunction. Thrombocytopenia is caused by disseminated intravascular coagulation (DIC), thrombotic microangiopathy (TMA), heparin-induced thrombocytopenia (HIT), antiphospholipid syndrome (APS), idiopathic thrombocytopenic purpura (ITP), etc. As DIC is classified according to the degree of fibrinolysis, it was stated that the measurement of hemostatic molecular markers was further required. TMA is caused by abnormality of ADAMTS13, verotoxin, DIC, etc. HIT is diagnosed by anti-PF4 antibody, but its specificity is not high. Further investigation of TMA and HIT is required. APS is one of the most important diseases which cause thrombosis or abortion, suggesting that a differential diagnosis of APS is important. It was reported that diagnostic criteria of ITP have been established using a new antibody assay for platelets, immature platelet fractions, thrombopoietin, etc. In myeloproliferative disorders such as polycythemia vera and essential thrombocythemia, the mutation of JAK2 V617F was reported to be an important risk factor for thrombosis.