Role of fibrinolysis in DIC. The dotted-line arrows summarize the reaction steps. Even with extensive thrombus, when fibrinolysis is inhibited by the action of PAI, plasmin formation is low, so the thrombi do not easily dissolve, and FDP and D-dimer elevations are mild (for example, DIC in sepsis). On the other hand, when PAI activity is low, plasmin formation increases, the thrombi dissolve more easily, and there are higher elevations of FDP and D-dimer (for example, DIC in APL). FDP and D-dimer are important markers for DIC, but their degree of elevation may not correlate with DIC severity (in particular, the degree of organ dysfunction). t-PA tissue type plasminogen activator, PAI plasminogen activator inhibitor, TF tissue factor, VIIa activated factor VII.