2019 Volume 68 Issue 3 Pages 519-524
The Clauss fibrinogen assay (CFA) has been widely used and determine functional fibrinogen levels. Although fibrinogen antigen (Ag) level determination is necessary for the diagnosis of fibrinogen abnormalities, few reagents and coagulation analyzers had been optimized for measuring fibrinogen Ag. In this study, we newly established an assay parameter to determine fibrinogen Ag level using the FactorAuto® Fibrinogen reagent, which is based on the latex immuno-agglutination assay for the CS-5100 analyzer. We assessed within-run and between-day imprecisions using two levels of control plasma. Dilution linearity and limit of detection of the fibrinogen antigen were also investigated. The correlation between functional fibrinogen and antigenic fibrinogen was analyzed using citrated plasma from patients without dysfibrinogenemia. This study was approved by the Nagoya University Hospital Ethics Committee. Within-run imprecision and between-day imprecision were <5%, and dilution linearity was up to 720 mg/dL. The limit of detection was 4.2 mg/dL when the sample volume was increased two-fold. The correlation between fibrinogen activity (CFA) and Ag (FactorAuto® Fibrinogen) was excellent and Spearman’s r was 0.9874. The excellent correlation between FactorAuto® Fibrinogen and N-assay TIA Fib for the antigen was observed and Spearman’s r was 0.988. Fibrinogen Ag levels determined by FactorAuto® Fibrinogen showed a significant difference (p < 0.005) compared with N-assay TIA Fib. These results suggest that the FactorAuto® Fibrinogen reagent is useful for routine laboratory tests. We observed a significant difference between the FactorAuto® Fibrinogen and the N-assay TIA Fib, and both reagents are available in CS-5100 analyzer. Taken together, automated fibrinogen antigen determination using the CS-5100 analyzer is available in clinical settings and could contribute to the diagnosis of fibrinogen abnormalities.
