Background: Detection of new oral anticoagulant (NOAC) levels by screening, special and global tests, and liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) is important in clinical situations when the cause of bleeding needs to be determined.
Methods: We compared a routine coagulation test, special function test for NOACs, global coagulation test, and an LC-MS/MS method that enables simultaneous determination of apixaban, dabigatran and rivaroxaban in human plasma within one analysis to determine the optimal indication of the comparison methods, including their limitations and interferences.
Results: This study was conducted on a set of blood samples from 116 patients treated with NOACs. The results of both specific dilute thrombin time (dTT) tests for dabigatran provided the same results as the activated partial thromboplastin time (aPTT) screening test in comparison with LC-MS/MS as a reference. The dTT assay HemosIL® showed better results for low concentrations when compared to LC-MS/MS than dTT HYPHEN® as HemosIL® uses a non-linear calibration curve. Results of the specific anti-Xa assay yielded better results than the prothrombin time test in comparison with LC-MS/MS as a reference, especially for apixaban, but also for rivaroxaban. Our LC MS/MS method is simply feasible, but only in a specialized laboratory. The method is easy-to-use for the simultaneous determination of all dabigatran, apixaban and rivaroxaban by LC-MS/MS within three minutes with a concentration range of 1 to 500 µg/L without dilution.
Conclusions: In the normal practice of the coagulation laboratory, it is advisable to use specific tests for NOAC determination as screening and global assays are not sufficiently specific. The dTT test is the optimal choice for dabigatran determination and for xabans to determine anti-Xa activity. The LC-MS/MS method is suitable as an arbitration method for serious conditions.