Heterogeneity of red cell volume: quantitation, clinical correlations, and possible mechanisms.

To permit quantitative study of red cell volume heterogeneity, the coefficient of variation (CV) of erythrocyte volume was determined in blood samples from 868 subjects, including normal individuals and those with various hematologic disorders. In groups of subjects with various hemoglobinopathies, CV increased above normal in parallel with the presence and degree of anemia. However, all subjects with iron, folate, or vitamin B12 deficiency showed marked increase in CV (anisocytosis): increased CV accompanied even early iron deficiency not yet associated anemia or microcytosis. Effects of other conditions on CV also were studied.