Multicentric evaluation of a new assay for prothrombin fragment F 1+2 determi-nation

A multicenter study of a recently developed ELISA for the determination of prothrombin fragment F1+2 was performed in order to evaluate analytical and clinical aspects. Mean intra-assay and inter-assay reproducibility were found to be 11.0 and 12.6%, respectively. The measuring range covered by the calibration curve reaches from 0.04 to 10.0nM/l F1+2. Testing 133 healthy subjects a reference range of 0.37 to 1.11nM/l F1+2 (2.5-97.5 percentile) with a median of 0.66nM/l F1+2 was calculated. Minor difficulties with blood sampling (venous occlusion for 2 min) did not affect F1+2 plasma concentrations. Significantly increased F1+2 levels were measured in patients with leukemia (p<0.0001), severe liver disease (p<0.005) and after myocardial infarction (p<0.01). Elevated F1+2 concentration before the beginning of heparin therapy (1.25nM/l) decreased to 0.77 nM/l (p<0.0001) after 1 day of therapy. For patients in the stable phase of oral anticoagulant therapy decreasing F1+2 concentrations were measured with increasing INR. F1+2 levels were already significantly reduced in patients with INR <2.0 (0.56nM/l; p=0.0005). Thus F1+2 determination may be helpful in identifying activation processes as well as in monitoring anticoagulant therapy.