As opposed to more traditional anticoagulants, NOACs do not require routine laboratory monitoring due to their predictable effectiveness and wide therapeutic windows. However, there is an increasing consensus among experts that laboratory measurements of the anticoagulant effect of NOAC may be useful in special circumstances.
The direct oral anticoagulants (NOACs) currently include one direct thrombin inhibitor (dabigatran) and three direct factor Xa inhibitors (apixaban, edoxaban, and rivaroxaban) with various approvals for treatment and prevention of thromboembolic events.
Dedicated NOAC special testing methods, found in Table 4, have been developed for laboratory use over recent years. Specific NOAC assays are recommended based on availability, although most are not widely available. These assays usually do not have turnaround times that would allow for use in urgent clinical situations. However, specimens for apixaban, edoxaban, or rivaroxaban analysis can be submitted to a reference laboratory.
Table 4. Recommended Assays for New Oral Anticoagulants in Plasma.| Drug | PT | APTT | TT | dTT | ECA | Anti-Xa |
| Dabigatran | No | No | Yes | Yes | Yes | No |
| Apixaban | No | No | No | No | No | Yes |
| Edoxaban | No | No | No | No | No | Yes |
| Rivaroxaban | No | No | No | No | No | Yes |
*Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the gold standard for quantitative assays for the measurement of NOACs (dabigatran, apixaban, edoxaban, and rivaroxaban) drug levels in plasma.
**
PT: prothrombin time;
APTT: activated partial thromboplastin time;
TT: thrombin time;
dTT: dilute thrombin time;
ECA: ecarin chromogenic assay;
anti-Xa: anti-factor Xa activity
