Patients with thrombocytosis have normal or slightly elevated thrombopoietin levels

Background and Objective. The distinction between clonal and reactive throm bocytoses Is a frequent problem and Implies different therapeutic options. As thrombopoietin (TPO) is the main regulator of megakaryocytopoiesis and t hrombopoiesis, we measured TPO levels in patients with thrombocytosis in an attempt to understand the regulation and potential utility of distinguishi ng thrombocytoses. Design and Methods. Serum TPO levels, platelet counts, mean platelet volume , hemoglobin, erythrocyte sedimentation rate and age were evaluated in 25 p atients with clonal thrombocytosis (15 with essential thrombocythemia, 6 wi th polycythemia vera and 4 with chronic myeloid leukemia) and in 50 patient s with reactive thrombocytosis distributed In three groups: 1) patients In post-surgical states; 2) patients with solid tumors; and 3) patients with i nflammatory diseases. Results. TPO levels were slightly Increased in patients with clonal (135+/- 50 pg/mL) and reactive (147+/-58 pg/ml) thrombocytosis compared with contro ls (121+/-58 pg/mL). Analyzing the different groups, patients with essentia l thrombocythemia had the lowest TPO levels (120+/-28 pg/ml) and patients w ith solid tumors the highest levels(162+/-59 pg/mL). patients with clonal t hrombocytosis were older, had higher platelet counts, mean platelet volume and hemoglobin, and lower erythrocyte sedimentation rate than patients with reactive thrombocytosis. Interpretation and Conclusions, Minor differences were observed in TPO leve ls between patients with primary and secondary thrombocytoses. Erythrocyte sedimentation rate, hut not TPO levels, may be a useful tool for discrimina ting both types of thrombocytoses, (C) 1999, Ferrata Storti Foundation.