1997 Volume 11 Issue 3 Pages 155-161
The relation between erythropoietin (Epo) and erythropoietic capacity was examined in 11 cases with hemolytic anemia (HA), 12 cases with aplastic anemia (AA), 30 cases with iron deficiency anemia (IDA) and 5 other cases, including 1 case with Dubowitz syndrome (DS). Plasma Epo, various hematologic parameters and peripheral blood erythroid progenitors (BFU-E and CFU-E) were assayed to assess correlation among them. As has been previously reported, a significant reverse correlation between Hb and plasma Epo level was obtained in respective anemic conditions. However, AA showed a higher Epo level as compared to other anemias with compatible lowering of Hb. Furthermore, a significant reverse correlation between Epo and peripheral CFU-E was observed only in the AA cases. With much interest, Epo increased to significant levels (more than 50 mU/ ml) in 3 of 4 HA cases, 3 of 7 AA cases and 1 of 5 IDA cases, in which the subject showed not so marked anemia (Hb≥11 g/dl) and a concomitant increase of peripheral BFU-E was observed, suggesting some stimulus to erythropoiesis was present. A patient with DS, a non-anemic case (Hb =12.5 g/dl) and also without abnormal Hb, showed a marked increase in Epo level (206 mU/ml) which was not associated with any increase of peripheral BFU-E. Theses findings indicate the possibility of an Epo stimulating mechanism beside tissue hypoxia. To understand the mechanism, additional experiments using animals were conducted for this study. Intraperitoneal injection of hemin to rats resulted in a marked increase in plasma Epo levels and a significant increase in reticulocyte counts. The degradating products of hemoglobin such as hemin may contribute to stimulating Epo secretion in various non-anemic condition.
