Human urinary megakaryocyte colony-stimulating factor in thrombopoietic disorders.

The level of urinary Meg-CSF activity in patients with various thrombopoietic disorders was studied. Five out of eight patients with idiopathic thrombocytopenic purpura had megakaryocytic hyperplasia in the marrow and increased Meg-CSF activity in the urine. Urinary Meg-CSF activity in patients with polycythaemia vera and essential thrombocythaemia was normal. There was a significant inverse correlation between urinary Meg-CSF activity and peripheral blood platelet count but not bone marrow megakaryocyte mass. There was a significant increase of urinary Meg-CSF activity during the period of thrombocytopenia after chemotherapy in patients with acute leukaemia who were in complete remission. The timing of maximal Meg-CSF levels corresponded to the nadirs of platelet counts. These results support the concept that Meg-CSF may play a significant role in the regulation of megakaryopoiesis and/or thrombopoiesis in vivo.