[Analyses of plasma thrombopoietin levels in patients with thrombocytopenia].

We measured plasma levels of thrombopoietin (TPO) in several patients with thrombocytopenia. Similar to previous reports, TPO levels in aplastic anemia (N=9) were markedly higher than those in idiopathic thrombocytopenic purpura (N=10): 16.19+/-9.07 fmol/ml and 1.21+/-1.06 fmol/ml, respectively. In patients with secondary failure of platelet recovery (N=7) as well as primary failure after hematopoietic stem cell transplantation, TPO levels were very high, reflecting impaired platelet production due to GVHD, drug treatments, and infection. When using new drugs such as TPO-receptor agonists, measurement of TPO levels might be important to differentiate the mechanism of thrombocytopenia.