Evaluation of thrombin reagent in Clauss fibrinogen assay: Switching from human-origin thrombin to bovine-origin thrombin

Abstract

Objectives: Plasma fibrinogen levels are determined by the Clauss fibrinogen assay (CFA) using thrombin reagent in routine laboratory tests. Thrombocheck Fib (L) is a liquid, ready-to-use reagent containing human-origin thrombin for CFA. In this study, we evaluated a new Thrombocheck Fib (L) reagent, which contains bovine-origin thrombin instead of human-origin thrombin. Methods: We compared two different lots of Thrombocheck Fib (L) reagent. One contained human-origin thrombin (Lot 209) and the other contained bovine-origin thrombin (Lot 212). We evaluated these two reagents by measuring their fibrinogen levels using the control plasma Coagtrol IX/IIX and plasma samples from patients. This study was approved by the Nagoya University Hospital Ethics Committee (Identification No. 2010-1083-2). Results: The reagent containing bovine-origin thrombin showed no significant differences in within-run imprecision, between-day imprecision, dilution linearity and limit of detection compared with the reagent containing human-origin thrombin. We also found no significant inhibition by interference substances. The correlation between Lots 209 and 212 was excellent and Spearman’s r was 0.9971. Discussion and Conclusion: There are few reports on the differences between human-origin thrombin and bovine-origin thrombin for plasma fibrinogen determination. In this study, we evaluated the bovine-origin thrombin reagent in comparison with the human-origin thrombin reagent and found no significant differences between them. Future studies should be carried out to assess the reactivities of these human- and bovine-origin thrombin reagents against abnormal fibrinogen or direct oral anticoagulants.