Table 3

Suggestions for Laboratory Measurement of DOACs When Specialized Assays are not Available

DrugClinical Objective
Exclude Clinically Relevant Drug LevelsDetermine Whether On-Therapy or Above On-Therapy Levels Are Present
Suggested TestInterpretationSuggested TestInterpretation
DabigatranTT, aPTTNormal TT excludes clinically relevant levels
Prolonged TT does not discriminate between clinically important and insignificant levels
Normal aPTT usually excludes clinically relevant levels, if a sensitive reagent is used.
aPTTProlonged aPTT suggests that on-therapy or above on-therapy levels are present
Normal aPTT may not exclude on-therapy levels, particularly if a relatively insensitive aPTT reagent is used
ApixabanNoneNormal PT and aPTT do not exclude clinically relevant levelsPTProlonged PT suggests that on-therapy or above on-therapy levels are present
Normal PT may not exclude on-therapy or above on-therapy levels, particularly if a relatively insensitive PT reagent is used
Edoxaban or rivaroxabanNoneNormal PT and aPTT do not exclude clinically relevant levelsPTProlonged PT suggests that on-therapy or above on-therapy levels are present
Normal PT may not exclude on-therapy levels, particularly if a relatively insensitive PT reagent is used

Anti-Xa = anti–factor Xa; aPTT = activated partial thromboplastin time; DOAC = direct-acting oral anticoagulant; PT = prothrombin time; TT = thrombin time.

  • The term “clinically relevant” refers to DOAC levels that may contribute to bleeding or surgical bleeding risk. The minimum DOAC level that may contribute to bleeding or surgical bleeding risk is unknown. The International Society on Thrombosis and Hemostasis recommends consideration of anticoagulant reversal for patients with serious bleeding and a DOAC level >50 ng/mL, and for patients requiring an invasive procedure with high bleeding risk and a DOAC level >30 ng/mL (17).