A COMPARISON OF D-DIMER AND SERUM FIBRINOGEN/FIBRIN DEGRADATION PRODUCT LEVELS (F.D.P.’s) IN THE INVESTIGATION OF HYPERCOAGULABLE STATES

D-Dimer assays measure specific breakdown products of crosslinked fibrin whereas FDP assays are not specific for these products. We have, therefore, measured D-Dimer levels (MabCo Dimer Test) semi-quantitatively in patients with clinical and laboratory evidence of disseminated intravascular coagulation, acute and chronic liver disease, acute leukaemia at presentation and acute venous thrombosis at diagnosis. We have also measured D-Dimer in the 3rd trimester of normal pregnancy and in pregnancies with complications. We compared these levels with F.D.P. levels measured by the Thrombo-Wellcotest. Patients with liver disease comprised mainly cirrhosis and acute viral hepatitis; those with venous thrombosis had this diagnosis confirmed by venography. Pregnancy complications included mainly pre-eclampsia, ante-partum haemorrhage and intra-uterine foetal death. D-Dimer levels were elevated ( 200ng/ml) in all 31 patients with D.I.C., in 34 of 40 with liver disease, in 13 of 16 with acute leukaemia, in all 10 patients with D.V.T., in 9 of 16 normal pregnancies and in 29 of 39 complicated pregnancies. Using a rank correlation method, there was correlation between D-Dimer and F.D.P. levels (Normal 8ug/ml) in the following groups of patients as follows (r is the correlation coefficient, levels of significance are shown in brackets):

D.I.C. r=0.72(0.2%), liver disease r=0.56(0.2%), acute leukaemia r=0.72(0.2%), D.V.T. r=0.83(1%) and complicated pregnancy r=0.42(1)6). There was no correlation between D-Dimer and F.D.P. levels in normal pregnancy. Very rarely were D-Dimer levels elevated when F.D.P. levels were normal and vice-versa. We conclude that a close relationship does exist between D-Dimer and F.D.P. levels in the clinical conditions that we have studied. We note the high incidence of elevated D-Dimer levels and the close correlation with F.D.P. levels in patients with liver disease and the high incidence of elevated D-Dimer levels suggesting increased activity of the coagulation system in patients with acute leukaemia.