Erythropoiesis during recovery from iron deficiency: normocytes and macrocytes.

In 26 patients with severe iron deficiency and microcytic anemia (MCV less than 70 fl), serial red cell size distribution histograms (erythrograms) were taken before and during iron therapy. Initially all patients had a single population of red cells, all microcytes. With the first reticulocytosis after iron therapy, a new population of cells appeared, larger in volume than the original. In 23 of 26 patients the new population of cells was of normal size (82-96 fl). In 3 of 26, the new population was macrocytic (MCV greater than 98 fl). Of these 3, 1 had folate deficiency; after folate was given, normocytes were produced. The other 2, both taking phenytoin and 1 a heavy alcohol using, had persistent macrocytosis despite folate administration. Erythrograms allowed quantitative, rapid evaluation of erythropoietic response to iron repletion. Abnormal macrocytic responses could be identified and seemed to occur with some frequency.