Performance of the Sysmex XN-V hematology analyzer in determining the immature platelet fraction in dogs: A preliminary study and reference values.

Background: Immature platelets (IPs) are newly formed platelets released into circulation that have been demonstrated as good markers of thrombopoiesis. Although many flow cytometric and fully automated-based methods are available, the latest Sysmex XN-V hematology analyzer for veterinary use is equipped with a specific fluorescent platelet channel (PLT-F) that detects platelets using a platelet-specific dye.

Objectives: The aims of this study were to evaluate the performance of the Sysmex XSN-1000 V in determining the IPF (immature platelet fraction) and other selected PLT-F channel parameters and to propose IPF reference intervals (RIs) for canine blood samples.

Methods: Canine EDTA blood samples were analyzed on the Sysmex XN-1000 V to assess linearity, imprecision, carryover, stability, and the effect of platelet clumping on selected platelet parameters from the PLT-F channel. We also reported the de novo generated RIs for the IPF in dogs.

Results: Imprecision was acceptable (CV <10%) for all parameters except for the absolute IPF values (IPF#), in which the reproducibility was 12.15% for the normal-low concentration samples. Linearity and carryover were excellent for all variables. Relative IPF values (IPF %) and IPF# remained stable for both storage conditions for up to 48 hours; however, a nonsignificant progressive increase in these parameters was observed from 12 hours at 4°C. We observed a statistical increase in IPF% and IPF# and a statistically significant decrease in PLT-F counts after intentional in vitro platelet aggregation. RIs were generated for all reference samples (n = 69) and for samples with (n = 25) or without (n = 44) platelet clumps.

Conclusions: The performance of the new PLT-F channel-derived variables for dogs was excellent. Specific RIs for IPF should be used when platelet aggregates are present.