Table 3.

Interpretation of coagulation assays in the setting of dabigatran toxicity [2, 25, 45, 56]

		Qualitative effect		Quantitative effect
	PT/INR	aPTT	TT	Dilute TT	ECT
Typical reference ranges	9.5–13.8 s/0.8–1.2	28–38 s	15–23 s	NAa	NAa
Relation to dabigatran plasma concentration	Linear	Curvilinear	Linear	Linear (r 2 > 0.90)	Linear (r 2 > 0.90)
Utility in the setting of toxicity	Not useful and should not be used. PT/INR does not correlate with dabigatran activity	Higher risk of bleeding with aPTT levels at troughs greater than two- to three-fold greater than baseline	At dabigatran concentrations >600 ng/mL, the maximum measurement of the TT is exceeded. TT is too sensitive for dabigatran concentrations >20 ng/mL	Values >65 s are associated with an excess risk of bleeding. Hemoclot® DTI assays are not approved for clinical use in the USA	Higher risk of bleeding with levels >3 times the upper limit of reference
Interpretation	Not relevant	If both tests are within reference ranges, this suggests no significant dabigatran effect is present. If results are elevated, then the degree of dabigatran’s effects is unclear		If either test result is within the reference range, then it suggests no significant effect from dabigatran is present

aPTT activated partial thromboplastin time, ECT ecarin clotting time, INR international normalized ratio, PT prothrombin time, TT thrombin time

^aNo reference values can be provided due to significant inter-laboratory variability. Reference ranges are determined from a calibration curve