Partial Thromboplastin Time (PTT)

If any of your clotting factors are missing, at a low level, or not working properly, your blood may not clot the way it should.

A PTT test helps check a specific group of clotting factors. It works as a screening test for problems in the intrinsic clotting pathway (factors VIII, IX, XI, and XII) and the common pathway (factors II, V, X, and fibrinogen), and it can also pick up on substances in the blood that block these factors from working. A PTT test is often done with other tests that check clotting factors and how well they all work together.

Your PTT test results will show how much time it took for your blood to clot. Results are usually given as a number of seconds. A PTT test is often ordered along with another blood test called a prothrombin time (PT) test. A PT test measures other clotting factors that a PTT test doesn't check. Your provider will usually compare the results of both tests to understand how your blood is clotting. Ask your provider to explain what your test results mean for your health.

If your blood took longer than normal to clot, or if it clotted faster than normal, it may be a sign of a problem with your clotting factors. Talk with your provider to learn what your test results mean.