T Watson P, MA, B; S Wattley SOC, PS; H Webster MS; J Webster E*, ME*, EL*, H; S White AD; J Whiteley PY, B, C; T Whiteley TT, TH; L Whitley BUS, SOC, MM; O Whittell P, MA, MS; C Whitwam PY, E/EL, ME*; A Whitworth MM; O Widdop PY*, SOC*, E*; C Wilcock PY, EL; M Wilford PY, ME, EL; I Wilinsky EL, PS, H, MM; B Wilkinson AD, ME.
Prothrombin time (PT) Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. A related blood test is partial thromboplastin time (PTT). A blood sample is needed. If you are taking ant blood-thinning medicines, you will be watched for signs of bleeding.
The prothrombin time (PT) â along with its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) â are assays evaluating the extrinsic pathway of coagulation. This test is also called ProTime INR and PT/INR.They are used to determine the clotting tendency of blood, in the measure of warfarin dosage, liver damage, and vitamin K status. PT measures factors I (fibrinogen) , II (prothrombin) , V, VII, and X.aboratory measurement [edit]. The reference range for prothrombin time depends on the analytical method used, but is usually around 12â13 seconds (results should always be interpreted using the reference range from the laboratory that performed the test), and the INR in absence of anticoagulation therapy is 0.8-1.2.