Examination of differentiation between fibrin strands specimens and platelet aggregation specimens using the PLT-Clumps flag of the XN series of automated hematology analyzers

Abstract

Sysmex XN has different detection performance of platelet aggregation depending on the platelet measurement mode. In this study, we utilized this difference to examine whether the presence or absence of the PLT-Clumps flags in each mode can differentiate fibrin strands from platelet aggregation when the same specimen is measured with PLT-I and PLT-F. Of the 18,540 specimens for which blood counts were requested, 757 were included in the study if they met the following criteria. (i) PLT decreased by more than 30% from the previous value; (ii) PLT-Clumps-flag was displayed; (iii) fibrin precipitation or platelet aggregation was observed, although the above conditions were not met. Then, sensitivity, specificity, and AUC were determined based on the Q-Flag value, which is the trigger for flagging, and specimen findings, and compared in each mode. Criteria were also developed to classify specimen characteristics as “negative,” “platelet aggregation,” or “fibrin strands” according to the presence or absence of the PLT-Clumps flag in each mode, and concordance with specimen findings was evaluated. The AUC for fibrin strands was significantly higher for PLT-F. Sensitivity and specificity for platelet aggregation were clearly lower for PLT-I (0.06, 0.65) than for PLT-F (0.87, 0.91). The concordance rate of the criteria was 98.7% for PLT-Clumps flags not in both modes (= negative), 99.5% for PLT-I only (= negative), 67.9% for PLT-F only (= platelet aggregation), and 92.0% for both modes (= fibrin strands). The results suggest that the combination of PLT-Clumps flags may be able to differentiate the cause of false low platelets.