Assessment of D‐dimer in Plasma: Diagnostic Value in Suspected Deep Venous Thrombosis of the Leg

Abstract

D-dimer, a fibrin degradation product containing the gamma-gamma crosslink of fibrin, can now be assayed by the use of highly specific monoclonal antibodies. Such assays are not influenced by fibrinogenolysis and measurements can be performed on citrated plasma. The diagnostic values of four such assays--two based on ELISA technique and two on latex agglutination--were evaluated in 108 out of 118 consecutive patients admitted with suspected deep venous thrombosis of the leg. With cut-off limits defined by a pilot study and with venography as reference, a negative D-dimer test was confirmed in 45 of 46 patients (98%; 95% confidence limits: 88-99.9%) after ELISA-M, in 43 of 44 (98%; 88-99.9%) after ELISA-S, in 54 of 67 (81%; 69-89%) after Latex-M and in 40 of 44 (91%; 78-97%) after Latex-S. A positive D-dimer test was confirmed in 61% (48-73%), 59% (46-71%), 63% (47-78%), and 55% (42-67%) respectively. These data suggest the use of one of the ELISA assays for screening. A negative D-dimer test excludes deep venous thrombosis, whereas a positive D-dimer should be followed by venography. By this procedure a 40% reduction of venographic examinations can be expected.