Intravenous gammaglobulin treatment for immune thrombocytopenia associated with infectious mononucleosis.

Severe thrombocytopenia is an uncommon (incidence less than 1%) but serious complication of infectious mononucleosis. Corticosteroids have been used for therapy with variable responses reported. Five consecutive patients with infectious mononucleosis-related severe thrombocytopenia were treated with intravenous gammaglobulin (IVIG) at a dose of 400 mg/kg/day for 2-5 days. All patients appear to have had an immunologic or consumptive etiology for their thrombocytopenia as determined by increased marrow megakaryocytes. All patients were initially treated with oral prednisone 1 mg/kg/day. Due to the relatively slow response to prednisone (platelet count less than 20,000/microliters on the 8th to 13th hospital day) or increased bleeding symptoms, IVIG was initiated. Four of the five patients rapidly developed significant increases in their platelet counts (range 44,000/microliters to 97,000/microliters). Two of these responses were sustained and two relapses occurred (while on continued steroid therapy) which again responded to booster doses of IVIG at similar doses. IVIG has been previously shown to be effective in treating patients with idiopathic thrombocytopenia purpura. Historically, patients with infectious mononucleosis-related severe thrombocytopenia often are refractory to corticosteroid therapy and our limited experience suggests that IVIG may also be effective in infectious mononucleosis-related severe thrombocytopenia.