Control of oral anticoagulant therapy.

In an effort better to standardize the control of oral anticoagulant therapy, it has recently been recommended that the prothrombin time be reported in the form of an International Normalized Ratio (INR) based upon calibration of the locally employed thromboplastin with an International Reference Preparation. It has been demonstrated in our laboratory that the INR does minimize the differences in results which ensue from variations in the source of thromboplastin and instrumentation and should hopefully allow for better interlaboratory comparisons in the future. Recent studies have also suggested that many American patients tend to be over anticoagulated and at greater risk for hemorrhage. Based upon those findings, over 40 percent of our specimens were above the currently recommended levels.