Potential utility of the new Sysmex XE 5000 red blood cell extended parameters in the study of disorders of iron metabolism

Background: New erythrocyte parameters are reported by the Sysmex XE 5000 analyzer. This instrument measures the hemoglobin (Hb) content of individual red cells, calculates the percentage of hypochromic red cells (%Hypo He) and the percentage of hyperchromic red cells (%Hyper He) and quantifies the proportion of marginally sized erythrocytes (%Micro R and %Macro R). The goals of the study were to establish the reference range for erythrocyte extended parameters, their value in different types of anemia and to investigate their reliability in the study of disorders of iron metabolism. Materials: Three hundred and ninety samples were analyzed. The Kolmogorov-Smirnoff test, independent samples t-test and Pearson correlation were calculated; receiver operating characteristic (ROC) curve analysis was used to determine their diagnostic performance. Results: The values of the four parameters studied were normally distributed and statistically different (p<0.0001) in the different groups of patients; the only exception was %Hypo He in cases of iron deficiency and thalassemia (p = 0.3758). Results of ROC curve analysis for %Hypo He in the diagnosis of restricted erythropoiesis reticulocyte Hb content (reticulocyte hemoglobin content, Ret He <29 pg) were: area under the curve 0.963; cut-off 1.8%; sensitivity 98.3%; specificity 91.1%. Conclusions: The new parameters appear to be sensitive for detecting small changes in the number of red cells with inadequate hemoglobinization and volume. Clin Chem Lab Med 2009; 47: 1411-6.