Reticulocyte count and its parameters: comparison of automated analyzers, flow cytometry, and manual method

With newer techniques, improvements have been made in reticulocyte counting, but variability is still there. In this study, we evaluated the three methods of reticulocyte counting, namely automated, flow cytometry, and manual methods for reticulocyte count and also for the enumeration of immature reticulocyte fraction (IRF). Reticulocyte count was done by manual method (light microscopy); two different automated analyzers, LH-780, Beckman Coulter, USA and Pentra-XLR, Horiba Ltd., Japan; and flow cytometry (FACS Canto II, B.D. Bioscience, USA). Also, the classification of stages of maturation was done, and percentage was counted based on quantity of reticulum and its distribution in the cytoplasm. Statistical analysis was done to compare statistical difference between methods. A total of 302 patient samples and 40 normal samples were included. For all automated methods, there is a tendency to overestimate with respect to microscopic methods. There is a strong correlation between manual and automated methods as well as among the 2 automated analyzers. The median IRF in LH-780 had a tendency to be on the higher side as compared with that in Pentra-XLR and manual method (p < 0.05). There is good correlation between the methods for reticulocyte counts. However, the normal values are dependent on the method used.