[Reliability of low platelet counts--comparison of microscopic counts with automated hematology analyzer XE-2100]

Sysmex XE-2100 is an automated hematological analyzer with excellent features that can count platelets by both impedance and optical fluorescent method. Particularly, it is notable that platelet counts by optical fluorescent method (PLT-O) are automatically adopted when platelet counts by impedance method (PLT-I) are less than 50 x 10(3)/microl or platelets have abnormal distribution. We compared PLT-I with PLT-O, and also with microscopic counts, using the samples with thrombocytopenia. Regarding reproducibility, mean coefficient of variation values were 5.3% in both PLT-I and PLT-O, when no flags of "PLT Abn Distribution" appeared in the samples with thrombocytopenia. Coefficient of variation values was 10.4% in PLT-I and 5.9% in PLT-O, when flags of "PLT Abn Distribution" appeared in the sample with thrombocytopenia. Correlation among the data obtained by PLT-I, PLT-O and microscopic counts were excellent. When a large difference was observed between PLT-I and PLT-O, PLT-O was more closely consistent with microscopic counts. PLT-O was useful compared with PLT-I, and this system was considered to measure platelet counts more correctly in the samples with thrombocytopenia. Thus, it was suggested that reliable platelet counts could be reported even in the samples with thrombocytopenia by switching system in XE-2100.