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.