The invention relates to a method for determining the total clotting activity of a blood or plasma sample, characterized in that a highly specific, reversible thrombin inhibitor is added to a blood or plasma sample in a defined amount, the clotting of the blood or plasma sample is induced and, after a defined period of time, the consumed amount of the added thrombin inhibitor is determined in a per se known manner, as well as to a kit for obtaining information about the state of coagulation of a blood sample.