Biomarker education

PT / INR: What It Measures & Why People Track It

Also called: Prothrombin time, INR, PT, Prothrombin time / INR

PT and INR are measurements related to how quickly blood forms a clot.

General biomarker education — not personalized medical advice. Learn more

Result on your report

Illustrative

PT / INR

—

Range: Low – High

LowReference intervalHigh

What it generally measures

Prothrombin time measures clotting speed in a blood sample; INR standardizes that result for comparison, especially when monitoring certain blood thinners.

Common units on reports: sec / ratio

Why people track it over time

People on anticoagulants often compare INR values across draws with their care team. Target ranges are individualized — this page does not set a target.

Changes over time do not by themselves establish a diagnosis. Learn more

Questions you might ask a healthcare professional

Questions to bring

Illustrative

Ask what INR range your clinician is aiming for in your case, if any.

Confirm medication timing and dose questions with your care team — not with an app alone.

Compare against the values and notes printed on your source report.

Organize your own lab history

Upload My Labs →

Part of Kind Panel education · Lab results guide

Continue learning

Reference range

PT / INR reference range

What the range on your report means for this marker.

← Browse all biomarkers