The traditional measurement is the mean corpuscular volume (MCV) but it is one of the last parameters to change with the onset of IDE. The latter can be detected earlier by an increased percentage of hypochromic erythrocytes measured by selected hematology analyzers, but it is also a relatively late indicator of IDE. On the other hand, the reticulocyte hemoglobin content (CHr) declines within a few days of the onset of IDE because of the short 1-2 day lifespan of circulating reticulocytes. Falsely normal values of the CHr can be observed with an elevated MCV or thalassemia but the main limitation to its wider use is that it can be measured by only one model of analyzer (Bayer Advia). The low specificity of the percent hypochromic erythrocytes and the CHr is reflected in a recent study reporting that 62% of predominantly anemic patients had abnormal values on admission to hospital.