Antithrombin Activity
If a patient takes dabigatran, and thrombin is the target enzyme for antithrombin measurement, then antithrombin activity will be overestimated as thrombin activity will be inhibited by antithrombin and dabigatran.
The same overestimation will occur when the patient's drug is an anti-factor Xa and the target enzyme used for testing is factor Xa. The extent of the overestimation could mask the diagnosis in patients with congenital heterozygous antithrombin deficiency.
Activated protein C resistance
Activated protein C (APC) resistance may be overestimated in patients on NOAC when measured with the APTT-based methods (with and without activated protein C).
