Serum thrombopoietin levels in acute myeloid leukaemia

To improve our understanding of the regulation of circulating platelet counts (PC) by thrombopoietin (TPO), we studied serum TPO levels and PC before and after myelosuppressive chemotherapy in 12 patients with acute myeloid leukaemia (AML). Serum TPO levels were measured by the quantitative sandwich enzyme-linked immunosorbent assay (Quantikine, RD Systems). At the start of the induction chemotherapy, the patients had a median serum TPO level of 199 pg/ml (range 120-2,150 pg/ml), while 10 to 12 days after the end of chemotherapy, their TPO levels were substantially increased, the median value being 1,907 pg/ml (range 1,049-4,194 pg/ml). The correlation between PC and TPO was statistically significant prior to chemotherapy (p < 0.03) and insignificant after chemotherapy. As a result of chemotherapy, the patients developed aplasia; after the administration of platelet transfusions, their median PC increased to 21 x 10(9)/l (range 5-55 x 10(9)/l), while the median TPO value decreased by 300 pg/ml (range 11-1,125 pg/ml). Our results suggest that platelet mass directly regulates serum TPO levels in acute leukaemia patients prior to chemotherapy and after the administration of platelet transfusions. Serum TPO levels may also be influenced by the cytokine response during complicating infections in patients with chemotherapy-induced cytopenia.