Two Cases of Pseudoelevation of Plasma Thrombin Time Levels

Thrombin is a protein involved in the clotting process and binds to free fibrinogen turning it into insoluble fibrin, causing blood to clot. Thrombin time (TT) is a test for the conversion of fibrinogen to fibrin on a common pathway and a screening test for the ability of a subject's plasma to convert fibrinogen to fibrin.

We reported two cases of abnormal extension of TT due to different reasons. We used magnetic bead method to detect thrombin time and used time unit sec to represent TT detection data.

In the two cases, we found the TT results of patients taking dabigatran are abnormally high, and normal plasma contaminated with heparin can also cause abnormally high TT results.

The influence of heparin on TT was the greatest, followed by activated prothrombin time (APTT), but the influence on prothrombin time (PT) and fibrinogen (FIB) was not obvious. TT is highly sensitive to dabigatran in blood, so TT is not suitable for monitoring dabigatran. The normal value of TT can be used to confirm whether dabigatran has drug residues. In addition, idarucizumab can be used to reverse the anticoagulant activity of dabigatran when dabigatran causes life-threatening bleeding or other high-risk bleeding surgeries.