Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.
What the test is
It's often done with PT/INR.
Why it's done
- Unexplained bleeding or bruising
- Before surgery
- Monitoring heparin
- Frequent miscarriages
Getting ready and what happens
- Tell your provider about blood thinners.
How the test is done
- A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.
What the results mean
| Result | Typical range for adults |
|---|---|
| PTT | About 25 to 35 seconds (labs vary) |
Normal ranges vary from lab to lab and can differ by age, sex, and pregnancy. Your report lists your lab's own range next to each result. A result a little outside the range is often not a problem.
Long
Can mean heparin effect, a clotting factor deficiency like hemophilia or von Willebrand disease, liver disease, or lupus anticoagulant.
Questions to ask your provider
- What do my results mean for me?
- Do I need to repeat this test or have other tests?
Risks
A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.
Related conditions
Related medicines
Related tests
Sources
Last updated 2026-11-13.