[Platelet production, clearance and distribution in patients with idiopathic thrombocytopenic purpura].

We have studied 8 normal subjects, and 12 patients with idiopathic thrombocytopenic purpura whose platelet counts ranged from 9 x 10(9)/L to 40 x 10(9)/L. Autologous platelets labeled with 111Intropolone were used for evaluation of mean platelet survival, platelet turnover, platelet sequestration sites, and platelet production (turnover) to clearance (sum of platelet uptake in the liver and the spleen) ratio. Platelet survival correlated directly with platelet counts. There was no significant correlation between the platelet sequestration pattern and platelet count, survival, or turnover. Sum of platelet uptake in the liver and the spleen showed a significant inverse correlation with platelet survival. No significant correlation was found between platelet turnover and platelet count. There was a significant correlation between the platelet production to clearance index when all subjects were analyzed. The distribution of platelet turnover showed considerable individual variation; eight of twelve patients showed platelet turnover less than mean minus 2SD of the control value, but others showed normal range. We conclude that although platelet destruction mechanism in RES shows a primary role of thrombocytopenia, impaired rate of effective thrombopoiesis may also contribute to disease severity in ITP.