Assessment of blood sample stability for complete blood count using the Sysmex XN-9000 and Mindray BC-6800 analyzers

BACKGROUND Different hematological analyzers have different analytical performances that are often reflected in the criteria for sample stability of the complete blood count. This study aimed to assess the stability of several hematological parameters using the XN-9000 Sysmex and BC-6800 Mindray analyzers. METHODS The impact of storage at room temperature and 4°C was evaluated after 2, 4, 6, 8, 24, 36 and 48h using ten normal and 40 abnormal blood samples. The variation from the baseline measurement was evaluated by the Steel-Dwass-Critchlow-Fligner test and by Bland-Altman plots, using quality specifications and critical difference as the total allowable variation. RESULTS Red blood cells and reticulocyte parameters (i.e. hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, red blood cell distribution width, immature reticulocyte fractions, low-fluorescence reticulocytes, middle-fluorescence reticulocytes, high fluorescence mononuclear cells) showed less stability compared to leukocyte and platelet parameters (except for monocyte count and mean platelet volume). The bias for hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration and red blood cell distribution width coefficient of variation was higher than the critical difference after 8h using both analyzers. CONCLUSION Blood samples measured with both analyzers do not show analytically significant changes in up to 2h of storage at room temperature and 4°C. However, the maximum time for analysis can be extended for up to 8h when the bias is compared to the critical difference.