The erythrocyte cell hemoglobin distribution width segregates thalassemia traits from other nonthalassemic conditions with microcytosis.

Red cell heterogeneity, as represented by the red cell distribution width (RDW), can be used to distinguish thalassemia traits from iron deficiency. Two other indices of heterogeneity, the hemoglobin distribution width and the cell hemoglobin distribution width (CHDW), are also available. In addition, the CHDW may reflect the process of cell hemoglobinization more accurately than does the RDW. In this study, recursive partitioning methods were used to compare the ability of these three indices to discriminate between thalassemia traits and other nonthalassemic conditions among hospital patients who had microcytosis. The data indicate that the CHDW can segregate patients who have either iron replete or iron deficient nonthalassemic conditions from those who have thalassemia traits. A CHDW level of less than 3.05 correctly discriminated 78.4% of patients in a mixed hospital sample. A CHDW/RBC ratio of 0.57 improved the segregation further, with a sensitivity of 79.2% and a specificity of 88.5% for the identification of a thalassemia trait.