西安交通大学医学院血液系统疾病课件 IDIOPATHIC.pptVIP

IDIOPATHIC THROMBOCYTOPENIC PURPURA Li Jing * Definition of the disease Idiopathic thrombocytopenic purpura (ITP) is an bleeding disorder due to immune destruction of platelets, low platelet count in peripheral blood. It is characterized by the : (1)haemorrhage of skin , mucosa and internal organs (2)thrombocytopenia (3)disturbance of marrow megakaryocytes in growth and maturity (4)shortened platelet survival and antibodies to specific platelet The clinical syndromes of ITP are distinct between acute ITP and chronic ITP. The incidence of acute ITP appears to be greater in children , and in children both sexes are equally affected in contrast to the female predominance in Chronic ITP which appearing to be greater in adults. In chronic ITP the female-to-male ratio is 4:1. Peak incidence occurs in adults aged 20-50 years. Peak incidence occurs in children aged 2-4 years. Approximately 40% of all patients are younger than 10 years. Cause and Mechanism Immune Factors immune factors may be the most important reason. Harrington and coworkers demonstrated in 1951 that infusion of whole blood or plasma from patients with ITP into normal volunteers caused thrombocytopenia the active principal in ITP plasma as gamma globulin, suggesting there are antiplatelet antibodies in ITP plasma. Antiplatelet antibodies can be measured in more than 80% ITP. It is termed as platelet associated immunoglobulin (PAIg), most of them are IgG witch is located on the platelet surface. the affirmatively curative effect with glucocorticoid ， plasmapheresis and gamma globulin. 2. Infection more relative to acute ITP. Upper respiratory infection can be found in 80% patients of acute ITP , 2 weeks before onset. Antibodies of virus and immunocomplex(IC) can be found in plasma for the pa