Test guide
Partial Thromboplastin Time (PTT) Test
A partial thromboplastin time (PTT) test uses a blood sample to measure the number of seconds it takes for your blood to 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, and your liver makes most of them.
What it is for
A PTT test is used to check for problems with a specific group of blood clotting factors. It's done to: Source: MedlinePlus, National Library of Medicine. Medical test information is public domain. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.
Limitations
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.
Also known as
- activated partial thromboplastin time, aPTT, intrinsic pathway coagulation factor profile
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