Prolonged anemia in an intrauterine-transfused neonate with Rh-hemolytic disease: no evidence for anti-D-related suppression of erythropoiesis in vitro

BACKGROUND: Rh-hemolytic disease may be complicated in some cases by a prolonged postnatal anemia with an extended need for postnatal red blood cell (RBC) transfusion. Besides ongoing hemolysis, marrow suppression and erythropoietin (EPO) deficiency are discussed as underlying mechanisms of this so-called "late hyporegenerative anemia." CASE REPORT: We present a case of a newborn with Rh-hemolytic disease caused by anti-D who received several intrauterine RBC transfusions. After birth, no reticulocytes or D+ RBCs were detectable in peripheral blood of the infant; thus further RBC transfusions were necessary. Administration of intravenous immunoglobulins had no obvious effect. Reticulocytes first became detectable 15 weeks after birth, when anti-D titer had decreased to 16. A few days later, hemoglobin started to increase and no further treatment was necessary. To investigate whether anti-D is able to cause maturation arrest of erythroid progenitors, maternal serum was added to an in vitro assay of erythropoiesis, induced from human CD34+ cells. RESULTS: In this case, no variables of hemolysis (e.g., elevated bilirubin) were observed. The EPO level was normal and a marrow sample showed increased erythropoiesis. The in vitro erythropoiesis assay revealed no influence of anti-D on RBC proliferation and differentiation. CONCLUSION: Anemia in our patient seemed to be mainly caused by ongoing intramedullar hemolysis due to persistent high anti-D titers. In such cases, variables for hemolysis are not necessarily found. Release of patient's own RBCs into the circulation may become sufficient when anti-D has declined to a very low level of approximately 16.