VII. TEACHING POINTS

1. Adult auto-immune thrombocytopenic purpura (AITP) occurs more often in women than men at a ratio of 2-3:1. In older age groups there may not be gender differences. The presenting signs may include mucosal bleeding, a petechial rash, or a low platelet count incidentally noted on a routine CBC.
2. AITP may occur as a separate entity (ITP) or in association with a medication, virus, autoimmune syndrome or a lymphoid malignancy. Childhood ITP is a similar entity but typically follows a viral illness and resolves spontaneously over weeks to months in 90% of patients.
3. AITP is characterized by thrombocytopenia with normal or increased megakaryocytes in the bone marrow. In most cases the diagnosis is made clinically and is confirmed by the response to therapy.
4. A corticosteroid is the first line therapy and, in most cases, raises the platelet count. Most adult patients will relapse at some point after tapering corticosteroid therapy. IVIg or anti-RhD (in Rh positive patients) is useful for the emergent treatment of severe thrombocytopenia. Patients usually have only brief responses to platelet transfusion, and therefore, it should be used only for severe life- or organ-threatening bleeding. Giving IVIg prior to the platelet transfusion may improve the response.
5. Adult AITP often becomes a chronic disease with a relapsing course. Patients often require additional treatment with steroids or second line therapies such as a splenectomy, rituximab, thrombopoietin mimetic agents, danazol, azathioprine or cyclophosphamide.