New fluorescent method (PLT-F) on Sysmex XN2000 hematology analyzer achieved higher accuracy in low platelet counting.

OBJECTIVES In thrombocytopenia, high accuracy and precision of low platelet count is essential for appropriate decisions. The recently introduced Sysmex XN2000 analyzer (Sysmex, Kobe, Japan) offers 3 methods for platelet counting: impedance (PLT-I), optical (PLT-O), and a new fluorescence method (PLT-F). The precision of the PLT-F method in blood samples with platelet counts less than 50 × 10(3)/μL (50 × 10(9)/L) was investigated and compared with the ICSH CD61-ImmunoPLT reference method. For comparison, PLT-I and PLT-O were determined on the Sysmex XN2000 and Sysmex XE2100 analyzer. METHODS Blood samples with platelet counts less than 50 × 10(3)/μL (50 × 10(9)/L) (n = 37) were analyzed on the Sysmex XN2000 and XE2100 analyzers. The CD61-ImmunoPLT method was performed on a Beckman Coulter FC-500 flow cytometer (Miami, FL). RESULTS At a platelet count of 20 × 10(3)/μL (20 × 10(9)/L), reproducibility for PLT-I, PLT-O, and PLT-F on the XN2000 demonstrated coefficients of variation of 9.3%, 8.5%, and 3.0%, respectively. Correlation between PLT-O on the XN2000 and XE2100 yielded an r value of more than 0.977. Linear regression analysis between the PLT-F and CD61-ImmunoPLT methods resulted in a PLT-F of 0.71*CD61 - 0.8 (r = 0.988). Linear regression between PLT-F and PLT-O on the XN2000 resulted in a PLT-F of 1.05*PLT-O - 2 (r = 0.975), and using the transfusion threshold of 20 × 10(9)/L platelets resulted in a PLT-F of 0.90*PLT-O - 0.4 (r = 0.956). CONCLUSIONS The new PLT-F method demonstrated excellent results for reproducibility in samples with platelet counts less than 50 × 10(9)/L. PLT-F could be helpful in making better decisions for platelet transfusions.