A REFERENCE MATERIAL FOR HARMONIZATION OF D-DIMER ASSAYS

The term ''D-dimer assay'' suggests, that these assays report the conc entrations of the end-stage degradation product of crosslinked fibrin. This hardly occurs in patients. Degradation products of cross linked fibrin rather occur with a wide range of molecular weights, and compri se various numbers of the D-dimer motif. Moreover, the numerical value s obtained with different ''D-dimer'' assays vary widely. The variatio ns are probably due to differences in reactivity of the various monocl onal antibodies used with the various D-dimer containing degradation p roducts as they occur in patients; and to the various calibrators with a value assigned by the manufacturers. For the reasons indicated abov e a calibrator in the strict sense (e.g. pure D-dimer) is not feasible . This study shows that: it appears feasible to generate a conversion factor for each of the ''D-dimer'' assays studied? which will make the widely varying results obtained with these kits comparable; that the conversion factors can be based on a pool of real patient samples; and that the conversion factors are pool-independent. The next and final step in this study is to prepare and make available an international r eference material for use by manufacturers and others facing a compari son problem. This is being carried out, in collaboration with the NIBS C (Dr. P. Gaffney), and the material is expected to, be available in e arly 1997.