Prothrombin Time
Alternate Names : PT
What do the test results mean?
The healthy range for a PT test depends on the standards
of the lab. It generally falls between 10 to 15 seconds. When a person is
taking blood thinners, the international normalized ratio, called the INR,
is calculated to determine the correct dosage of the medicine. High PT
values may occur when a person:
is taking blood-thinning medicines, especially warfarin
is taking other medicines, such as certain antibiotics, that interfere
with the test
has severe liver disease
has disseminated intravascular clotting,
called DIC, a complex blood disorder that occurs when clotting mechanisms are
activated throughout the body
has certain rare, inherited bleeding disorders
has a vitamin K
deficiency
Abnormally low PT values are usually not significant.
However, they may occur when a person:
has cancer
has blood clots
is taking certain medicines, such as birth control pills
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