Platelet kinetic studies in patients with idiopathic thrombocytopenic purpura

PURPOSE: To determine the value in diagnosis and treatment of mean platelet life, platelet production, and major sites of platelet destruction in patients with idiopathic thrombocytopenic purpura (ITP). PATIENTS AND METHODS: Sternal or posterior superior iliac spine bone marrow aspiration was performed in 141 patients. Platelet kinetic studies with Indium-111 tropolonate labeled autologous platelets were utilized to determine platelet production. RESULTS: Two subgroups of patients could be defined. The first group (n = 81, 58%) had normal or increased platelet production and increased peripheral platelet destruction. These patients fulfilled the conventional criteria for ITP, including reduced platelet survival time (mean ± SD, 1.6 ± 1.4 days). Forty-eight (59%) of these patients had increased splenic sequestration and 30 (88%) of the 34 patients who underwent splenectomy had a complete or partial remission. The second group (n = 60, 42%) had decreased platelet production, with significantly greater platelet survival times (3.6 ± 2 days, P<0.0001). In this group, the proportion of patients with complete or partial response to splenectomy (62%) was somewhat lower (P = 0.09). These patients mainly had ineffective platelet production in the bone marrow. CONCLUSIONS: Platelet kinetic studies suggest that ITP is a heterogeneous disease that comprises two subgroups. Further studies are needed to validate these findings and to determine their effect on the choice and outcome of therapy.