Pathophysiology of fibrinolysis.

The observed association between abnormal fibrinolysis and a tendency toward bleeding or thrombosis demonstrates the (patho)physiological importance of the fibrinolytic system. Deficient fibrinolysis represents an important haemostatic abnormality associated with thrombosis. A decreased fibrinolytic activity may be due to a defective synthesis and/or release of tissue-type plasminogen activator (t-PA) from the vessel wall, to a deficiency or functional defect in the plasminogen or fibrinogen molecule or more frequently to increased levels of t-PA inhibitor. Alternatively, excessive fibrinolysis due to increased levels of t-PA, to alpha 2-antiplasmin deficiency or to plasminogen activator inhibitor-1 (PAI-1) deficiency, may result in bleeding tendency.