partialThromboplastinTimePTTTest
Reviewed
A PTT test measures the number of seconds it takes for your blood to clot. It helps check how many of a specific group of clotting factors you have and how well they are working. The test is used to find the cause of too much bruising or bleeding, monitor people taking heparin, check for clotting problems related to autoimmune diseases such as lupus and antiphospholipid syndrome, and assess bleeding risk before surgery if you have a history of excessive bleeding.
Preparation and collection
You don't need any special preparations for a PTT test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- There can be a difference between how fast your blood clots in a test setting and how fast it clots in your body.
- Autoimmune diseases can affect your PTT test results by showing a slower clotting time than you actually have.
- Even if your sample clotted faster or slower than usual, that doesn’t necessarily mean you have a medical condition.
What to do next
Talk with your provider to learn what your test results mean for you. If your results are unusual, your provider may order more tests.
Evidence source
U.S. National Library of Medicine: partialThromboplastinTimePTTTest