In multiple myeloma increased thrombopoietin (Tpo) production may be involved in the maintenance of platelet production

In multiple myeloma (MM), suppression of haematopoiesis occurs as a result of expansion of malignant cells in the bone marrow. Thrombopoietin (Tpo) le vels in patients with impaired platelet production are generally found to b e highly elevated. To examine the circulating Tpo levels in patients with M M, Tpo levels were measured in 50 serum samples from 34 patients. Tpo level s were subsequently related to disease stage, and cell numbers and markers, i.e. platelet count, leukocyte count and haemoglobin (Hb) concentration. E levated Tpo levels were found in association with decreased platelet counts (n=8), but also in patients with normal platelet counts (n = 14). The latt er group included patients without and with signs of impaired haematopoiesi s, i.e. with decreased Hb concentration and decreased leukocyte count. Thes e results show that neither platelet counts nor Tpo levels are reliable par ameters to judge bone-marrow failure in patients with MM. Furthermore, in p atients with MM, increased Tpo levels may play a role in the maintenance of thrombocytopoiesis. The origin of the increased Tpo levels remains to be d etermined.