Serum thrombopoietin levels in acute myeloid leukaemia

To improve our understanding of the regulation of circulating platelet coun ts (PC) by thrombopoietin (TPO), we studied serum TPO levels and PC before and after myelosuppressive chemotherapy in 12 patients with acute myeloid l eukaemia (AML). Serum TPO levels were measured by the quantitative sandwich enzyme-linked immunosorbent assay (Quantikine, RD Systems). At the start o f the induction chemotherapy, the patients had a median serum TPO level of 199 pg/ml (range 120-2150 pg/ml), while 10 to 12 days after the end of chem otherapy, their TPO levels were substantially increased, the median value b eing 1907 pg/ml (range 1049-4194 pg/ml). The correlation between PC and TPO was statistically significant prior to chemotherapy (p <0.03) and insignif icant after chemotherapy. As a result of chemotherapy, the patients develop ed aplasia; after the administration of platelet transfusions, their median PC increased to 21 x 10(9)/1 (range 5-55 x 10(9)/1), while the median TPO value decreased by 300 pg/ml (range 11-1125 pg/ml). Our results suggest tha t platelet mass directly regulates serum TPO levels in acute leukaemia pati ents prior to chemotherapy and after the administration of platelet transfu sions. Serum TPO levels may also be influenced by the cytokine response dur ing complicating infections in patients with chemotherapy-induced cytopenia .