A partial thromboplastin time (PTT) test uses a blood sample to measure how long it takes for your blood to make a clot . Normally, when you get a cut or injury that causes bleeding, many different types of proteins in your blood work together to make a clot to stop the bleeding. These proteins are called coagulation factors or clotting factors.
If any of your clotting factors are missing, at a low level, or not working properly, your blood may:
- Clot too slowly after an injury or surgery. If this happens, you have a bleeding disorder . Bleeding disorders can cause serious blood loss. Hemophilia is one type of bleeding disorder.
- Clot too much and/or too quickly, even without an injury. This condition may lead to clots that block your blood flow and cause serious conditions, such as heart attack , stroke , or clots in the lungs .
A PTT test helps check a specific group of clotting factors. It helps show how much of these clotting factors you have and how well they're working. A PTT test is often done with other tests that check clotting factors and how well they all work together.
Other names: activated partial thromboplastin time, aPTT, intrinsic pathway coagulation factor profile