Description
Prothrombin time (PT) and partial thromboplastin time (PTT) are blood tests that measure how long it takes for blood to clot:
Prothrombin time (PT)
- Measures how long it takes for the plasma (liquid portion) of blood to clot. It evaluates the extrinsic system and factors common to both systems. PT results can be used to create an international normalized ratio (INR), which helps compare results from different labs or test methods.
Partial thromboplastin time (PTT)
- Measures how long it takes for blood to clot and evaluates the intrinsic system and the common components. PTT is used to monitor a person's response to heparin, an anticoagulant.
A PTT or PT test may be ordered if you have symptoms of a bleeding or clotting disorder, such as: Nosebleeds, Bruising, Heavy menstrual periods, Blood in the stool or urine, and Bleeding gums.
Fasting not required.
