[Monitoring for oral anticoagulant therapy].

Warfarin has been widely used for an oral anticoagulant therapy against thrombotic diseases. For the monitoring of its anticoagulant intensities, prothrombin time (PT) ratio and percentage of thrombotest (TT) are commonly used in Japan. Recently, International Normalized Ratio (INR) was recommended by ICSH/ICTH. Practicality and usefulness of INR and its combined use of thrombin-antithrombin III complex (TAT) for the monitoring of oral anticoagulation therapy were evaluated among patients of ischemic heart disease with or without interventions, and of cardiomyopathies and valvular diseases. Difference in thromboplastin sensitivities have been shown to cause errors in PT elongation and in the evaluation of anticoagulant activity, so that the monitoring only by PT ratio is considered to be irrelevant, and that INR is recommended to be used. INR was comparable to the levels of TT. Majority of the patients, whose TAT levels were kept normal, were controlled below the proposed therapeutic ranges of INR. With the combination of INR and TAT monitoring, anticoagulant effect of warfarin could be achieved safer in lower dose than the levels that might cause bleeding accidents.