What is fibrinolysis?

Fibrinolysis is a process that occurs inside the body to break down thrombus (blood clots). This prevents blood clots from remaining in place and growing and allows the body to clear fragments of clots safely to avoid risks such as strokes and damage to the heart that can be caused by big floating clots.


Primary fibrinolysis occurs naturally as the body clears clots that are no longer necessary once the underlying tissue is healed. Secondary fibrinolysis can be induced with medications or occur as the result of stress or disease.

When blood clots, it forms around a matrix of fibrin, a protein that is released during coagulation. The fibrin creates a framework for blood to clot around for the purpose of sealing a hole or covering a wound. Left in place, however, the clot could lead to the development of problems. In fibrinolysis, an enzyme called plasmin cuts through the fibrin to break the clot apart into smaller pieces that can be expelled by the body.

The precursor to plasmin, plasminogen, is produced in the liver. When blood starts to clot, plasminogen is locked inside the clot along with an activator that can turn the plasminogen into plasmin. As healing progresses, the activator is released to create plasmin to break up the clot. The body can also use inhibitors that interfere either with the action of the activator or the plasmin to slow fibrinolysis. This keeps the breakup of blood clots in balance.

Fibrinolytic agents are the compounds that breakdown the fibrin inside the clot but not the thrombus (blood clot) itself.