Test Details: Thrombin is an enzyme in blood that acts on the clotting factor fibrinogen to form fibrin, helping blood to clot. It measure the time that takes thrombin to convert fibrinogen into fibrin. The thrombin time assesses the activity of fibrinogen. This assesses the activity of fibrinogen and is used to investigate excessive bleeding or inappropriate blood clot formation. It is used to diagnose blood coagulation disorders and to assess the effectiveness of fibrinolytic therapy.