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 simultaneously determined reticulated platelet counts in whole blood by FACScan flow cytometry and serum thrombopoietin (TPO) concentrations by a sensitive 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 differ significantly from the normal range (1.43 ± 0.62 fmol/l). The patients with aplastic anemia (AA) had decreased reticulated platelet counts and markedly increased serum TPO concentrations (13.65 ± 10.64 fmol/l). In thrombocytopenic patients with liver cirrhosis (LC), the absolute number of reticulated platelets (1.65 ± 1.11 x 10⁹/l) decreased similarly that in AA. However, serum TPO concentrations (1.38 ± 0.50 fmol/l) did not increase in contrast to AA. Our findings suggested a possible dual mechanism of thrombocytopenia in LC; that is, thrombocytopenia in LC results from the decreased TPO production primarily in the liver adding to an increase in platelet sequestration in the spleen.