Coagulation reference ranges

Parameter	Units	Normal range	Therapeutic range
INR	Ratio	0.8 - 1.2	2.0 - 3.0*
APTT	Seconds	24-38	50 - 85 secs
FIBRINOGEN	g/L	1.5-4.0	N/A
TCT	Seconds	15 - 21	N/A
D DIMER	ug/L	<50 yrs 500 51-60yrs 600 61-70yrs 700 71-80yrs 800 >80yrs 900	N/A
FVIII	iu/dl	50 - 150	N/A

*The INR therapeutic range may be higher for conditions such as heart valves, recurrent thromboembolism or arterial thromboembolism with associated antiphospholipid syndrome.

Reviewed August 2025