Skip to main content
. 2019 Aug 6;20(5):770–783. doi: 10.5811/westjem.2018.5.38235

Table 1.

Laboratory testing of hemostasis.

Test Range Components Tested Medications
Prothrombin Time (PT/INR) 12–13 sec/0.8–1.2 Tissue factor pathway and common pathway (II, VII, X) Warfarin, anti-Xa agents (rivaroxaban*, apixaban*, edoxaban*)
Partial Thromboplastin Time (PTT) 30–60 seconds Contact activation and common pathways (all factors except factor VII) Heparin, factor II inhibitors (dabigatran**)
Anti-Xa Assay 0.0 Factor X LMWH, anti-Xa agents (rivaroxaban*, apixaban*, edoxaban), fondaparinux
Thrombin Time 12–14 seconds Factor II activity Factor IIa inhibitors (dabigatran)
Ecarin Clotting Time (ECT) 22.6 to 29.0 seconds
At trough: >3x the upper limit of normal suggests bleeding risk
Factor II activity Factor IIa inhibitors (dabigatran)

PT/INR, prothrombin time/international normalized ratio; LMWH, low-molecular-weight heparin.

*

PT is frequently elevated with these agents but a prediction as to the degree of anticoagulation is unreliable with these agents.

**

PTT is useful in determining the presence of an anti-factor II activity, however it cannot be used to monitor the degree of anticoagulation produced by these medications.