The relation of TPO levels to platelet counts in various disorders of platelet production

Serum TPO levels were measured using a quantitative ELISA assay in 118 healthy volunteers, 39 patients with consumptive thrombocytopenia (eg, ITP, DIC), 49 patients with hypoproliferative thrombocytopenia (eg, acute leukemia, stem cell transplantation), and 34 patients with thrombocytosis due to myeloproliferative disorders. The mean TPO level in healthy volunteers was 39 pg/mL (interquartile range, 7 to 99 pg/mL). In consumptive thrombocytopenias (gray squares), TPO levels were increased (median, 63 pg/mL; range, 48 to 98), with a median platelet count of 73,000/microL (range, 28,000 to 146,000/microL). By contrast, in hypoproliferative thrombocytopenias (white diamonds), serum TPO levels were significantly higher (median 706 pg/mL; range, 358 to 1546 pg/mL), with similar platelet counts (median, 59,000/microL; range, 30,000 to 117,000/microL). In myeloproliferative disorders with thrombocytosis (black triangles), TPO levels were similar to consumptive thrombocytopenia (median, 87 pg/mL; range, 38 to 126pg/mL), despite the high platelet counts (median, 550,000/microL; range, 413,000 to 693,000/microL). All patients in these studies had normal liver function.