True regarding prothrombin time measurement? -

Normal prothrombin time is 10-14 seconds So, from the given options prothrombin time should be measured within 2 hours is selected The prothrombin time (PT) - along with its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) - are assays evaluating the extrinsic pathway and common pathway of coagulation. This blood test is also called protime INRand PT/INR. They are used to determine the clotting tendency of blood, in the measure of warfarindosage, liver damage, and vitamin K status. PT measures the following coagulation factors: I (fibrinogen), II (prothrombin), V (proaccelerin), VII (proconvein), and X (Stua-Prower factor). The reference range for prothrombin time depends on the analytical method used, but is usually around 12-13 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. The target range for INR in anticoagulant use (e.g. warfarin) is 2 to 3. In some cases, if more intense anticoagulation is thought to be required, the target range may be as high as 2.5-3.5 depending on the indication for anticoagulation. Ref Robbins 9/e pg 450