Definition:

Plasminogen activator inhibitor type 1 (PAI-1) deficiency is a disorder resulting in increased fibrinolysis and an associated bleeding diathesis. PAI-1 is an important component of the coagulation system that down-regulates fibrinolysis in the circulation. Affected individuals exhibit mild to moderate bleeding symptoms, including epistaxis, menorrhagia, and delayed bleeding after trauma or surgical procedures. Spontaneous bleeding events are rarely seen in contrast to other procoagulant deficiencies. Generally most of the PAI-1-related diseases are due to elevated antigenic concentrations and their inhibitory activity. However, absence of cellular PAI-1 activity also causes several diseases. Clear documentation of PAI-1 deficiency as a cause of a bleeding disorder has been rare.