Evaluation of the mechanism causing anemia in infants with bronchopulmonary dysplasia.

In seven patients with bronchopulmonary dysplasia and anemia, we evaluated the mechanisms causing the anemia. All had a normocytic, normochromic, hyporegenerative anemia (mean hematocrit 26%; range 21% to 30%). The low hematocrit values seemed physiologically significant because mean (+/- SD), heart rates fell after transfusion (162 +/- 7 to 149 +/- 9 beats/min; p less than 0.005), as did blood lactate concentrations (1.2 +/- 0.3 mumol/gm blood before vs 0.5 +/- 0.3 after transfusion; p less than 0.05). Anemia could not be explained by blood withdrawal or deficiency of vitamin E, folate, or iron. No dyserthropoietic or megaloblastic changes were observed. No erythroid regenerative response was seen in the marrow; however, when recombinant erythropoietic growth factors were added to marrow cells in tissue culture, erythroid cell growth in vitro was normal. In contrast to patients with the "anemia of chronic disorders," these patients had a normal or increased number of marrow sideroblasts and increased serum transferrin saturation. Serum concentrations of erythropoietin were low for patients with anemia (range 11.4 to 47.1 mU/ml); yet the in vitro sensitivity of bone marrow erythroid progenitors (colony-forming units--erythroid) to recombinant erythropoietin was increased (p less than 0.001). We conclude that the anemia in these patients was the result of deficient production of erythropoietin, and we speculate that administration of recombinant erythropoietin would correct the anemia.