Prothrombin Time levels: what's normal, high and low
How long it takes blood to clot via the extrinsic pathway. Used to monitor warfarin therapy.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Prothrombin Time is measured with a standard blood draw; no fasting is needed. A typical reference range is 11.0 – 13.5 seconds. At TestWell it's $23.99 all-in as Prothrombin Time with INR, results in 1–3 business days, drawn at Quest. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- seconds / sec
- Sample
- Blood draw
- Fasting
- Not required
- Results
- 1–3 business days
- Price
- $23.99
- Labs
- Quest
Prothrombin Time Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+ | 11.0 – 13.5 seconds |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
What your Prothrombin Time result may mean
Often reflects warfarin therapy, vitamin K deficiency, or liver disease.
What a high Prothrombin Time means: causes, symptoms, next steps →Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
How do you get a Prothrombin Time test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Prothrombin Time is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Prothrombin Time with INR | This marker only | $23.99 |
| Blood Clotting Panel | 4 tests | $149.99 |
Quest vs. Labcorp for Prothrombin Time: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | Yes | $23.99 |
| Labcorp | No | — |
| BioReference (NY & NJ) | No | — |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Frequently asked
Often reflects warfarin therapy, vitamin K deficiency, or liver disease. A single result above the reference range is a prompt to look closer with a clinician — often a repeat test and related markers — not a diagnosis on its own.
Ready to test your prothrombin time?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $23.99.