[Measurement of prothrombin fragment F1+2 for monitoring the anticoagulant effect of phenprocoumon].

It was the aim of this study to ascertain whether the plasma level of prothrombin fragment F1+2 is a suitable indicator of the anticoagulant effect of coumarin derivatives. The F1+2 levels were measured in 164 patients (100 women, 64 men; mean age 63.3 [34-83] years) in whom stable anticoagulation had been achieved with phenprocoumon, comparing the results with those obtained in healthy subjects (28 women, 19 men; mean age 54.6 [25-72] years) without anticoagulation. There was a significant reduction (P < 0.0005) in F1+2 plasma levels with oral anticoagulation (0.45 + 0.23 vs. 0.67 + 0.32 nmol/l). Even on a low degree of anticoagulation (international normalized ratio [INR] < 2.0) the F1+2 value was reduced to within the normal range (0.32-1.2 nmol/l). These results indicate that changes in the plasma level of prothrombin fragment F1+2 are directly dependent on the degree of oral anticoagulation and that this measure seems suitable for the monitoring of the anticoagulant effect. This is also true for oral anticoagulation of mild degree (INR < 2.0) in which the effect cannot be satisfactorily measured by the thromboplastin time (Quick test).