THE DIAGNOSIS of anemia is dependent on the correct use and interpretation of laboratory procedures. While these have been in large part morphologic, in recent years measurements of blood production and destruction have led to an understanding of the alterations in marrow function in anemia. These erythrokinetic measurements are sufficiently quantitative and practical to receive general clinical application. The purpose of this discussion is to integrate erythrokinetics with the morphologic approach to anemia.
Anemias have been classified as microcytic, macrocytic, or normocytic (Table I). The alterations in cell size are identified either by examination of the stained blood smear or by calculation of the mean cell volume from the red blood cell count and hematocrit. Hemoglobin constitutes most of the erythrocyte's fixed mass, and the size of the mature cell is largely determined by its hemoglobin content. Thus, microcytosis reflects a quantitative impairment in hemoglobin synthesis. This