Prothrombin fragment F 1 + 2 and oral anticoagulant therapy

This study was undertaken to establish a correlation between prothrombin activation fragment F 1 + 2 and one-stage prothrombin time (PT) ratios in patients receiving oral anticoagulant therapy. One hundred consecutive patients on warfarin treatment were utilized for this study. The patients had received warfarin for not less than four days prior to entry into the study. F 1 + 2 levels and PT ratios were found to be 0.28 +/- 0.24 nM/L (mean +/- SD) ranging from 0.01 to 1.5 nM/L and 1.62 +/- 0.46 (mean +/- SD) ranging from 0.97 to 3.11, respectively. Most patients on oral anticoagulants with PT ratios between 1.2 - 1.7 exhibited decreased concentrations of F 1 + 2. Normal control values of F 1 + 2 were established for this study in 40 healthy individuals; they were 0.40 +/- 0.23 nM/L (median +/- SD) ranging from 0.11 to 1.19 nM/L. Mean plasma levels of F 1 + 2 were significantly lower in the anticoagulated patients as compared to the healthy controls (t = 2.377, p < 0.05). The relationship between F 1 + 2 levels and PT ratios in the 100 anticoagulated patients was analyzed by linear regression. No significant correlation (r = -0.208) was found between F 1 + 2 levels and PT ratios. It is concluded that the degree of reduction in F 1 + 2 levels is not proportional to the intensity of therapy reflected by the PT ratios in anticoagulated patients.