Fibrinolysis is a normal body process that keeps naturally occurring blood clots from growing and causing problems.

Primary fibrinolysis refers to the normal breakdown of clots.

Secondary fibrinolysis is the breakdown of blood clots due to a medical disorder, medicine, or other cause.

Blood clots form on a protein called fibrin. The breakdown of fibrin (fibrinolysis) can increase under certain conditions, such as:

• Bacterial infections
• Intense exercise
• Low blood sugar
• Not enough oxygen to tissues

In some situations, doctors may wish to speed up the rate of fibrinolysis. For example, when an abnormal clot forms in the blood vessels of the heart and results in a heart attack, human-made fibrinolytic substances (such as tPA, streptokinase, or Retavase) may be given to break up the clot.