Summary
A multicenter study of a recently developed ELISA for the determination of prothrombin
fragment Fl+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 10.0 nM/1 Fl+2. Testing 133 healthy subjects a reference range of 0.37 to 1.11
nM/1 Fl+2 (2.5–97.5 percentile) with a median of 0.66 nM/1 F1+2 was calculated. Minor
difficulties with blood sampling (venous occlusion for 2 min) did not affect Fl+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 (1.25
nM/1) decreased to 0.77 nM/1 (p <0.0001) after 1 day of therapy. For patients in the stable phase of oral anticoagulant
therapy decreasing Fl+2 concentrations were measured with increasing INR. Fl+2 levels
were already significantly reduced in patients with INR <2.0 (0.56 nM/1; p = 0.0005). Thus Fl+2 determination may be helpful in identifying activation processes
as well as in monitoring anticoagulant therapy.
