Stability of leukocyte research parameters over time on the Sysmex XN: How to quantify the changes in cell morphology

Research parameters of the Sysmex XN-series provide information about the cell morphology. The aim is to quantify time-dependent changes of conventional and research parameters and propose correction factors to be applied to the parameters, which revealed significant changes.

284 EDTA blood samples were processed from 0 hours-12 hours and the mean percentage change ( $$ %) of the leukocyte parameters was calculated. Stability was evaluated according to three criteria: metrology criteria according to the between-batch analytical variation, metrology criteria according to within-run analytical variation, by which $$ % could not exceed the Minimum Significant Change (MSC = [±1.65*CV%]) and Biological criteria based on intraindividual biological variation, by which $$ % could not exceed the Desirable Significant Change (DSC = [±0.5*CV_D %]). Mean deviation percentage of the parameters, which suffer significant changes was calculated and a multiplying factor was obtained to correct the signal deviation. Stability of abnormal leukocyte flags was also evaluated.

Most of the cell count parameters are considered stable according to MSC and DSC. However, several research parameters of neutrophils and lymphocytes show alterations in stability after 4 hours, even when their respective cell count parameters are stable.

Morphological variations of neutrophils and lymphocytes can be quantified. This data can be used to correct the deviation in samples that cannot be analyzed before 4 hours.