Partial Thromboplastin Time (PTT) Test Test
A PTT test measures how long it takes your blood to clot. It checks a specific group of clotting factors to see if they are missing, low, or not working properly.
What this test measures
A partial thromboplastin time (PTT) test uses a blood sample to measure how long it takes for your blood to make a clot. It helps show how much of certain clotting factors you have and how well they're working.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
If your blood took longer than normal to clot on a PTT test, it may be a sign of liver disease, a lack of vitamin K, certain genetic disorders like hemophilia, too much heparin, certain types of leukemia, or autoimmune diseases such as antiphospholipid antibody syndrome.
Lower-than-normal results
If your blood clotted faster than normal on a PTT test, it may be a sign of the early stage of disseminated intravascular coagulation (DIC) or advanced cancer of the ovaries, colon, or pancreas.
Frequently asked questions
What is a PTT test used for?
A PTT test is used to check for problems with a specific group of blood clotting factors. It can help find the cause of too much bruising or bleeding, find the cause of clotting problems, monitor people taking heparin, and check the risk for bleeding problems before surgery.
How is the PTT test done?
A PTT test uses a blood sample to measure how long it takes for your blood to make a clot.
What do PTT test results mean?
Results are usually given as a number of seconds. If your blood took longer than normal to clot, it may indicate certain conditions. If it clotted faster than normal, it may also indicate certain conditions. Your provider will explain what your results mean.
Is the PTT test always done before surgery?
No, a PTT test is not always used as a routine test before surgery. It may be used for certain people who may have a risk for bleeding problems.
What other tests are often done with the PTT test?
A PTT test is often ordered along with a prothrombin time (PT) test, which measures other clotting factors that a PTT test doesn't check.
Related lab tests
Sources
- MedlinePlus: Partial Thromboplastin Time (PTT) Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.