[Standardized prothrombin time determinations and optimal anticoagulant therapy].

WHO and other international organizations have recommended the introduction of a standardized prothrombin time determination. This would allow a universal scale for the intensity of oral anticoagulation therapy to be used. A prerequisite is the use of thromboplastin, calibrated against the international reference thromboplastin, standardized methodology etc. This permits every prothrombin time determination to be expressed as International Normalized Ratio (INR). The introduction of INR facilitates the implementation of optimal oral anticoagulation as defined by larged international studies.