1. ITP Immune (Idiopathic) Thrombocytopenic Purpura AM Report 5/25/2010

2. Definition Autoimmune disorder resulting in destruction of platelets Classified as primary vs secondary, and acute (<6 mos) vs chronic Among adults, the most common age group is 18-40 yrs More common in females (2-3:1)

3. Pathophysiology 1) Macrophages digest membrane GPIIb/IIIa or GPIb/IX phagocytosed platelets 2) Macrophages then present the antigens to autoreactive CD4+ T cells and thereby activate them 3) T cells exert helper activity on autoreactive Ab producing B cells 4) B cells produce Ab to platelets marking them for phagocytosis & destruction by macrophages

4. Pathophysiology Often there is compensatory increase in platelet production, however this can be impaired by – 1) intramedullary destruction of Ab coated platelets by macrophages OR – 2) inhibition of megakaryocytopoiesis

5. Clinical Features Mucocutaneous bleeding Purpura (petechiae, ecchymoses) Normal lymph node exam, no splenomegaly w/primary ITP

6. Diagnosis One of exclusion Isolated thrombocytopenia is present Associated conditions, drugs, or other thrombocytopenia inducing agents are NOT present Lab Data: -CBC w/diff looking for isolated thrombocytopenia - Peripheral smear

7. Secondary ITP Drugs (heparin, quinidine, sulfazalazine) Lymphoproliferative disease (CLL, lymphoma) SLE APLA syndrome Hepatitis C infection HIV CVID EBV IgA deficiency Sarcoidosis

8. Treatment Usually initiate with platelets <20 or <50 w/ bleeding Corticosteroids are first line – Decadron burst 40 mg daily x 4 days vs – Prednisone 1-2 mg/kg over 2-6 wks with taper IVIG Rituximab Anti –D Azathioprine Cyclosporine Cyclophosphamide Vinca alkaloids Danazol Splenectomy: considered when fail medical therapy w/ plt counts <30 for 4-6 weeks

9. Prognosis Fatal bleeding occurs from ICH with risk greatest in elderly Mortality rates 0.3-5% However, some believe the higher mortality rates are not reflective of modern practices and treatments and therefore estimate lifelong incidence of major bleeding and death from bleeding to be <1%