Effects of storage of blood at room temperature on hematologic parameters measured on Sysmex XE-2100

Blood specimens are frequently delivered to the clinical laboratory after a significant post-collection interval. On weekends, this interval may exceed 72 hours. When such a specimen arrives, the laboratory must decide whether to accept or reject the specimen. If accepted, the laboratory must then decide whether to perform all of the tests ordered or only those deemed appropriate given the age of the specimen, and what comments should be appended to the reported results regarding the reliability or limitations of the analysis. Storage of K2-EDTA-anticogulated blood at room temperature for up to 4 days caused changes in some but not all hematologic parameters measured on Sysmex XE-2100 analyzer. Specifically, the WBC, RBC, HGB, and PLT were found to be stable for up to 3 days. Retic % and #, but not the IRF, were stable for the duration of the study. Diff results may be unreliable or voted out by the analyzer on specimens that are 2 day old or older. The NRBC counts changed little on the average but revealed consistently wide 95% confidence intervals throughout.