Are prothrombin fragment 1+2 and thrombin-antithrombin complexes useful in the management of oral anticoagulant therapy?

We investigated the behavior of prothrombin fragment F1+2 and thrombin-antithrombin complexes in 70 patients treated with chronic anticoagulant therapy. Moreover, in a longitudinal study 37 patients were evaluated twice and 16 patients three times. Twenty-eight age- and sex-matched healthy subjects were also studied as a control group. Prothrombin fragment F1+2 and thrombin-antithrombin complexes were significantly higher in controls than in patients on anticoagulants. There were no differences in prothrombin fragment F1+2 or thrombin-antithrombin values among patients with different International Normalized Ratios, nor in the same patients studied two or three times. Our results confirm that oral anticoagulant treatment can effectively reduce thrombin activity. However, strong anticoagulation does not induce a further significant decrease in fragment F1+2 values. Therefore, we feel measurement of fragment F1+2 might be less useful than thought in optimizing oral anticoagulant therapy.