EVALUATION OF THROMBOPOIESIS IN THROMBOCYTOPENIC DISORDERS BY SIMULTANEOUS MEASUREMENT OF RETICULATED PLATELETS OF WHOLE-BLOOD AND SERUM THROMBOPOIETIN CONCENTRATIONS

To evaluate thrombopoiesis in thrombocytopenic disorders, we simultane ously determined reticulated platelet counts in whole blood by FACScan flow cytometry and serum thrombopoietin (TPO) concentrations by a sen sitive sandwich ELISA. The subjects were 40 healthy volunteers and 45 thrombocytopenic patients. In idiopathic thrombocytopenic purpura (ITP ), the percentage of reticulated platelets was significantly elevated (5.61 +/- 2.02%: mean +/- SD) relative to normal controls (2.17 +/- 0. 90%), but serum TPO concentrations (1.91 +/- 1.27 fmol/l) did not diff er significantly from the normal range (1.43 +/- 0.62 fmol/l). The pat ients with aplastic anemia (AA) had decreased reticulated platelet cou nts and markedly increased serum TPO concentrations (13.65 +/- 10.64 f mol/l). In thrombocytopenic patients with liver cirrhosis (LC), the ab solute number of reticulated platelets (1.65 +/- 1.11 X 10(9)/l) decre ased similarly that in AA. However, serum TPO concentrations (1.38 +/- 0.50 fmol/l) did not increase in contrast to AA. Our findings suggest ed a possible dual mechanism of thrombocytopenia in LC; that is, throm bocytopenia in LC results from the decreased TPO production primarily in the liver adding to an increase in platelet sequestration in the sp leen.