PB1101 - Measurement of fibrinogen using two concentrations of Thrombin with patients receiving Argatroban or normal plasma spiked with Argatroban: a review of UK NEQAS (Blood Coagulation) exercises 2021.

Tuesday, July 12, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

CR

Christopher Mark Peter Reilly-Stitt, MSc

Deputy Programme Manager
UK NEQAS BC
Sheffield, England, United Kingdom

Co-Author(s)

SG

Susan Guy

Senior Biomedical Scientist
Royal Hallamshire Hospital
Sheffield, England, United Kingdom
IJ

Ian Jennings

Programme manager
UK NEQAS BC
Sheffield, England, United Kingdom
Steve Kitchen, PhD

Lead Scientist
Sheffield Haemophilia and Thrombosis Centre
sheffield, England, United Kingdom
IW

Isobel Walker

Director
UK NEQAS BC
Sheffield, England, United Kingdom

Background: Measurement of fibrinogen with the Clauss assay is a thrombin time-based method that can be affected by Direct Thrombin Inhibitors. Argatroban is a direct thrombin inhibitor used in patients being treated for HIT and VITT.

Aims: To highlight the relative sensitivities of Clauss thrombin assays to argatroban.

Methods: A supplementary exercise for argatroban and fondaparinux included samples containing argatroban from a pool of treated patients and from a spiked normal plasma. Participants were requested to return Fibrinogen assay results. In addition, a regular Laboratory Programme exercise (survey 249) included a sample for fibrinogen assay from a patient undergoing plasma exchange and receiving argatroban for VITT.

Results: Samples distributed as part of an argatroban exercise (A21:01-05) and as part of the laboratory programme (249 21:31) in 2021 are detailed in table 1.

Conclusion(s): Commercial reagents for Fibrinogen quantitation have a range of thrombin concentrations and it is clear that the level of argatroban in patient or spiked samples can interfere with the measurement of fibrinogen. The data from the samples distributed highlight the fibrinogen underestimation with some assays in samples with levels of argatroban at therapeutic levels. Manufacturer’s inserts do not describe any assay limitation with regard to argatroban or other direct thrombin inhibitor.