Changes in erythropoiesis during the course of polycythaemia vera.

Using 58Fe, 51Cr and cytological parameters, the authors have examined erythropoiesis in 44 polycythaemia vera patients diagnosed as such on the basis of the usual parameters (exept for determination of the erythropoietin level). In the patients divided into four types the following characteristica were observed. In type I, increased erythropoiesis is evident by accelerated plasma iron clearance, greater PIT and EIT as well as enhanced iron utilization and production indices. In type II, in addition to the former signs of increased erythropoiesis moderately shortened red cell life-span and hyposideraemia characteristic of splenic sequestration and resulting from bleeding and blood letting seem to be accompanied by microcytosis. There is a metaplastic erythropoiesis in type III, bone marrow activity decreases, but the increased erythropoiesis is indicated by several parameters already observed earlier. At the time the iron utilization indicative of effective erythropoiesis is decreased, thus ineffective erythropoiesis and considerably shortened red cell life-span are responsible for the enhanced iron turnover. This is also shown by the regression calculations. In type IV effective erythropoiesis was considerably decreased in the patients with severe anaemia. Sings which are indicative of metaplastic erythropoiesis are absent. In one of the patients the morphological changes characteristic of dyserythropoiesis were found. Although all our patients were given treatment. We believe that these alterations in the character of erythropoiesis are not likely to be the consequences of therapy.