Prothrombin Time

Prothrombin Time (PT):
Measures the amount of time to form a clot. Measure of extrinsic coagulation pathway (prothrombin is converted to thrombin in first step of pathway). Used to monitor oral anticoagulant therapy with warfarin.
Increase  warfarin; Vitamin K deficiency; liver disease (cirrhosis, hepatitis, biliary obstruction); salicylate intoxication, fibrinogen deficiency, prothrombin deficiency, deficiency of factor V, VI, X.