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Bleeding Disorders

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Excessive Clot Breakdown

Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. In fibrinolysis, a fibrin clot, the product of the coagulation cascade, is broken down by a factor called plasmin. Normally, an activator (which converts inactive plasminogen to active plasmin) is released into the blood very slowly by the damaged lining (endothelium) of the blood vessels, such that, after several days (when the bleeding has stopped and injury healed), the clot is broken down.

The fibrinolytic process is tightly regulated by several other factors, especially plasminogen activator inhibitor (PAI) and plasmin inhibitor (e.g., alpha2-antiplasmin). If there is an inherited or acquired deficiency in one of the inhibitors, the fibrinolytic activity is enhanced. As a result, the clot is not as stable as it should be and is broken down early, causing excessive or prolonged bleeding, which typically occurs after an injury or invasive procedure (e.g., tooth extraction, surgery).

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