Erythropoietin course in newborns with Rh hemolytic disease transfused and not transfused in utero.

This study reports the Hb, erythropoietin (Epo), and reticulocyte course at different postnatal ages (range, 8-83 d) of 56 blood samples from 30 newborns (range, one or two blood samples from each newborn) with erythroblastosis fetalis (18 intrauterine transfused (IUTd) and 12 non-IUTd). Hb, Epo, and reticulocyte values were not statistically different in IUTd and non-IUTd cases. As age increased, decreasing Hb values and increasing Epo levels were observed. The reticulocyte count was relatively low in all but six cases. There was an inverse correlation between Epo and Hb (r = -55, p < 0.001), but no correlation was found between Hb and reticulocytes or between Epo and reticulocytes. When groups were formed on the basis of Hb levels, anemic newborns showed higher serum Epo than did nonanemic patients (p < 0.02). In the present study we found a significant increase in Epo levels in anemic newborns without a rise in the reticulocyte count. These results suggest that other mechanisms, rather than low Epo production, could be involved in the pathogenesis of this anemia. Persisting anti-D antibodies, probably at a medullary level, may destroy erythrocyte precusors, leading to anemia with a low reticulocyte count.