Different types of purpura are viewed with different blood markers. For example, allergic purpura may present with a normal platelet count, and idiopathic thrombocytopenic purpura and thrombotic thrombocytopenic purpura may present with a decreased platelet count. 1.allergic purpura: normal or increased white blood cells, neutrophils and eosinophils may be increased, platelet count is normal. 2. Idiopathic thrombocytopenic purpura: platelet count is reduced and the mean platelet volume is large. There may be varying degrees of normocytic or microcytic hypochromic anemia. 3. Thrombotic thrombocytopenic purpura: Elevated reticulocytes are seen, fragmented red blood cells >2%, and platelet count may be very low. Diagnosis of purpura in addition to blood, but also need to be combined with other test results to jointly determine, such as myelocytology, etc., the results of the laboratory should be timely to bring the results of the hospital follow-up, by the doctor based on the results of the examination of the comprehensive judgment.