F2 and deep vein thrombosis: She was taking Coumadin (warfarin) due to a history of recurrent deep vein thrombosis (DVT) so her prothrombin time and international normalized ratio (INR) were elevated at 28.2 seconds (normal range, 10.0 to 11.3 seconds) and 2.74 (target range, 2.0 to 3.0 for DVT treatment) respectively.