Influence of fibrinogen degradation products on thrombin time, activated partial thromboplastin time and prothrombin time of canine plasma

To investigate how thrombin time, activated partial thromboplastin time (AP TT) and prothrombin time are influenced by fibrinogen degradation products (FDP), different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 and 1.0 mg/ml) of the purified FDP X, Y, D and E were added to the plasma of health y dogs. If fragment Y was added to the plasma a considerable inhibitory eff ect could be demonstrated for all three test systems. A significant prolong ation (p < 0.05) was found for concentrations of greater than or equal to 0 .1 mg/ml (thrombin time, APTT) and greater than or equal to 0.2 mg/ml (prot hrombin time). With FDP Y concentrations from >0.185 mg/ml (prothrombin tim e) to >0.24 mg/ml (APTT) coagulation time was prolonged beyond the respecti ve reference range. As regards the other fragments, a comparable inhibitory effect could only be shown for fragment X added to the thrombin time test system. This effect can most probably be explained by the competition of th e FDP X and fibrinogen for the fibrinogen binding sites of thrombin, rather than by a fibrin polymerization disorder. The results demonstrate that for plasma with normal fibrinogen concentration the group tests are only prolo nged beyond the reference range at FDP concentrations very rarely found in spontaneous hyperfibrinolysis. Copyright (C) 2000 S. Karger AG. Basel.