Comparison of testing methods for reticulated platelets

Objective To compare the accuracy,stability and sample cross-contamination of two independent methods of detecting the percentage of reticulated platelets in peripheral blood and establish a local normal reference range so as to provide methodological rationales in clinical laboratory.Methods The percentages of reticulated platelets in peripheral blood of a healthy population were measured by Sysmex XE-5000 blood cell analyzer with polymethyl oxazine staining and flow cytometer with thiazole orange staining respectively.The correlation between the results of two methods was analyzed by Spearman's nonparametric correlation.Information about stability was obtained from measurements of the percentages of reticulated platelets in peripheral blood at designated timepoints.The analyses of accuracy,sample cross contamination and local normal reference range were performed routinely.Results The coefficient of variation (CV) of data was lower (16.2％) than that from flow cytometer (35.1％).The sample cross-contaminations of two methods were the same at around 5％.The percentage of reticulated platelets in peripheral blood was stable and consistent whereas the results of flow cytometer fluctuated at different timepoints within 4 h after blood sampling.The correlation of results obtained from two methods was significant (P ＜ 0.01,r2 =0.923).The local normal reference range was 1.0％-7.5％ for Sysmex XE-5000 versus 3.0％-10.5％ for flow cytometer.Conclusions Fully automalic blood cell analyze is more advanced than flow cytometer for its simple operation and stable data.And the former is an ideal first-choice for detecting the percentage of reticulated platelets in peripheral blood. Key words: Platelet count;  Flow cytometry;  Immature platelets