Variability of the erythropoietic response in autoimmune hemolytic anemia: analysis of 109 cases.

One hundred-nine cases of autoimmune hemolysis were reviewed to determine the frequency of reticulocytopenia, the state of the erythroid marrow in reticulocytopenic cases, and the course of reticulocyte production indices with time and glucocorticoid treatment. The mean hematocrit at presentation was 24 mL/dL, but 30% of cases had an initial hematocrit less than 20 mL/dL. Median reticulocyte percentage at diagnosis was 9%, and median reticulocyte production index was 2.8 times basal. Twenty percent of cases had an initial reticulocyte count less than 4%, and 37% had an initial reticulocyte production index less than 2.0 times basal. These reticulocytopenic patients were nearly evenly distributed between warm and cold antibody-mediated cases and between primary and secondary cases. Fifty-four percent of reticulocytopenic cases had a bone marrow examination during hospitalization. Three-fourths of these marrows showed erythroid hyperplasia, and erythroid hypoplasia was seen in only one case. Eighty-eight cases had serial reticulocyte measurements, and in only 15% of patients did the reticulocyte production index remain less than 2.0 times basal. Thus, in most cases, the initially low reticulocyte production index may represent a lag in marrow responsiveness to hemolytic stress. In cases with persistent reticulocytopenia, ineffective erythropoiesis is suggested by the frequency of marrow erythroid hyperplasia. In the cases that were initially reticulocytopenic and demonstrated an increase in reticulocyte production index, the magnitude of this increase was significantly greater in glucocorticoid-treated patients than in those not so treated, indicating that a glucocorticoid sensitive component exists in the marrow erythropoietic response to hemolysis. Awareness of the frequency of an initial reticulocytopenia in cases of autoimmune hemolysis may be important in initial diagnosis and treatment.