Method to determine the concentration of anticoagulants

A method to determine a presence or concentration of an anti-coagulant in a sample, the method comprising:

• a) combining the sample with a clotting factor reagent comprising prothrombin wherein the prothrombin is added in an amount in excess of amounts present in normal samples, an activator of coagulation in an amount sufficient to initiate coagulation, and a thrombin substrate;
• b) measuring thrombin formation;
• and
• c) determining the presence or concentration of the anticoagulant by correlating thrombin formation of the sample with thrombin formation of samples containing known concentrations of said anti-coagulant.

A kit to determine a concentration of an anticoagulant in a sample comprising:

• a. a first vessel containing a clotting factor reagent comprising prothrombin wherein clotting factors are in excess of a concentration of said clotting factors present in a normal sample;
• b. a second vessel containing an activator reagent;
• and
• c. a third vessel containing a thrombin substrate.