Blood Clotting (Coagulation) — Reference Ranges

Coagulation tests measure how well and how quickly the blood forms a clot. They are used when clotting seems too slow or too fast, and to monitor some anticoagulant (blood-thinning) treatments.

This page lists all 11 tests in this group with their typical adult ranges in both unit systems. Open any test for plain-language notes on high and low results and how to prepare.

Print this reference sheet

Test	Abbr.	Typical range (conventional)	Typical range (SI)
Activated Partial Thromboplastin Time	aPTT	25–35 sec	25–35 sec
Antithrombin	AT	80–120 %	80–120 %
D-Dimer	—	<500 ng/mL FEU	<0.50 mg/L FEU
Factor VIII	FVIII	50–150 %	50–150 %
Fibrinogen	—	200–400 mg/dL	2.0–4.0 g/L
International Normalized Ratio	INR	0.9–1.2 ratio	0.9–1.2 ratio
Protein C Activity	—	70–140 %	70–140 %
Protein S Activity	—	60–140 %	60–140 %
Prothrombin Time	PT	11.0–13.5 sec	11.0–13.5 sec
Thrombin Time	TT	14–21 sec	14–21 sec
von Willebrand Factor Antigen	vWF Ag	50–150 %	50–150 %

Full, always-updated version of this sheet: https://www.medicalvideos.com/lab-values/panel/coagulation/
Printed from MedicalVideos.com Lab Values. Educational reference only — not medical advice.

Please note: Reference ranges vary between laboratories, and between the methods and instruments they use — the range printed on your own report is the one your result should be compared with. A result outside the range is not by itself a diagnosis, and a result inside it does not rule out illness. These pages are an educational summary, not medical advice: always discuss your results with the clinician who ordered them, who can interpret them in the context of your health and history.

Blood Clotting (Coagulation) — Reference Ranges

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