The patient's history, physical examination, and smear/ marrow studies are consistent with a diagnosis of autoimmune idiopathic thrombocytopen ic purpu ra (AITP). ITP secondary to a relapse of his lymphoprol iferative disorder needs to be ru led out by additional studies, including thoracic and abdominal scans for lymphadenopathy and flow cytometry of blood and marrow to detect re-emergence of clonal disease (see Chapter 22).Assays for anti-platelet or platelet glycoprotein-specific antibodies are not routinely recommended to confirm AITP, due to their poor sensitivity and specificity. The diagnosis is primarily made by exclusion of other causes of thrombocytopenia and response to immunosuppressive therapies. Because of the patient's very low platelet count, he was hospital ized and started on IV methylprednisolone, I g/d x 3 days. By day 4, the platelet count had increased to 25,000/-tL, but he continued to have epistaxis and bleeding from the gums. He was subsequently begun on IV immune globulin, I g/kg/d x 2 days. His platelet count increased to greater than 1 50,000/-tL by hospital day 7, and he was discharged on oral prednisone (I mg/kg/d) with outpatient follow-up. The patient was counseled in the need for careful, long term follow-up, since adult AITP patients are highly likely to develop chronic or relapsing disease, the latter especial ly when attempting to decrease or discontinue corticosteroids. Many adu lt AITP patients wi ll require additional courses of therapy, including immunosuppressive agents such as Rituxan. Splenectomy may also be considered in refractory and corticosteroid-dependent patients. As for the new thrombopoietin-mimetic drugs, their role in managing chronic ITP remains to be defined.