Another challenging question from Pam Owens at TriCore Reference Laboratories, Albuquerque: We have a patient on Dabigatran (Pradaxa) for multiple deep venous thromboses (DVTs) while on warfarin. While the results of his lupus-like inhibitor (LLI, lupus anticoagulant, LAC) testing do not look as wild as someone on argatroban, we did get a positive result on the DRVVT (ratio 1.27 with a cutoff of 1.18). Can dabigatran give us a false positive on DRVVT? We know it can on hexagonal phase phospholipid. We’re not even going to touch the protein C and S by clotting assay.
Dean Willett, Director of Marketing at Precision BioLogic responded that we haven’t done any studies with respect to patients on Dabigatran (or any other DTIs) but I think it’s safe to assume that there might be some interference with many clot-based assays.
George remarks that here is another (perhaps off-label) application of Dabigatran: a substitute for warfarin therapy when warfarin is ineffective. Dean and George would agree that any clot-based assay is likely to be prolonged by a direct thrombin inhibitor. With the ever-increasing use of the new oral DTI, we will continue to see issues like this.
The above comment was provided by Dr. Larry Smith at Memoria
The above comment was provided by Dr. Larry Smith at Memorial Sloan-Kettering Cancer Center. Thank you, Larry, your experiment validates Dean Willett’s prediction. Geo.
George, I’ve run some normal samples spiked with Dabigatran
George, I’ve run some normal samples spiked with Dabigatran and have gotten false positives dRVVT’s.
LS