Incidence and possible reasons for discordant results between positive FDPand negative D-dimer latex assays in clinical specimens

In general, FDP and D-dimer values have a correlation in clinical condition s associated with disseminated intravascular coagulation(DIC) or coagulatio n activation. However, there are some patients with discordant results who demonstrate elevated FDP and negative D-dimer results by latex agglutinatio n assays. The incidence and possible reasons for the discordance between FD P and D-dimer results were investigated through simultaneous measurements ( n = 763) from clinical patients with suspected DIC or coagulation activatio n. 24.8% (189/763) of samples with elevated FDP were negative for D-dimer a ssays by the latex agglutination method. Further detailed analysis on rando mly-selected discordant samples (n = 41) revealed that the most common reas on fur the discordance was the lower sensitivity of the semiquantitative la tex agglutination method for D-dimer, compared with quantitative enzyme or other latex immunoassay. The other contributing factors to the discordance were accelerated fibrinogenolysis without: secondary fibrinolysis, elevated soluble fibrin monomer and rheumatoid factor.