PT / INR
A measure of blood clotting time — also reflects liver function.
What is it
Prothrombin time measures how long blood takes to clot via the extrinsic clotting pathway. The INR (international normalized ratio) standardizes results across labs.
Why it's measured
PT/INR has been used in evaluating clotting function, monitoring warfarin therapy, and assessing liver synthetic function in clinical research.
Reference range
Standard laboratory reference
INR 0.9 – 1.1 ratio
Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.
What results may indicate
Elevated
Elevated INR has been associated with clotting impairment, warfarin therapy, and liver dysfunction in research literature.
Lower
May indicate hypercoagulability in certain settings.
These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.
When it's measured
Used in clotting evaluation and as part of liver synthetic function assessment.
Related markers
Common questions
Prothrombin time measures how long blood takes to clot via the extrinsic clotting pathway. The INR (international normalized ratio) standardizes results across labs.
It's one of the markers used to build a fuller picture of your health. On its own it tells you very little, so it's most informative when reviewed alongside related markers.
It's measured from a standard blood draw at Quest or LabCorp. Prothrombin Time / INR is one of the markers included in the OPTML Apex Panel, where your results are read across systems and reviewed by a U.S.-licensed physician.
Reference ranges vary by laboratory, and a single value rarely tells the whole story. Review your result with a physician in the context of your other markers, symptoms, and history.
Prothrombin Time / INR is one signal among many. Answer a few quick questions and we’ll point you to the panel that fits.
Measured in
A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.
Find the right panel →This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.
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