The Influence of Anticoagulants and Time of Measurements on D-Dimer Determinations

Background : We evaluated the effects of anticoagulants used in blood sampling and time of mesurements after blood collection on D-dimer determinations. Methods : A total of 32 samples of sodium citrated plasma, and 23 samples each of serum and ethylene diamine tetraacetic acid (EDTA) plasma, were studied. D-dimer was measured by enzyme linked fluorescent assay using a VIDAS analyzer. Results : The meanSD (median) of D-dimer titers in citrated plasma, serum, and EDTA plasma samples immediately after blood collection were 282.7201.1 (224.6)g/L, 255.1206.8 (197.3) g/L, and 313.3230.8 (246.4)g/L respectively. The results obtained for the three different sample groups were well correlated. While the upper limit of the reference range for D-dimer for citrated plasma has been set at 500g/L, the cut-off values for serum and EDTA plasma were 400g/L (100% sensitivity and specificity), and 585g/L (100% sensitivity and 94.7% specificity), respectively Conclusions : In addition to citrated plasma, both serum and EDTA plasma can be used for D-dimer assay. A delay in the time of measurements after blood collection does not influence the results significantly.