DefinitionFibrinolysis 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.Alternative NamesFibrinolysisCauses, incidence, and risk factorsBlood clots form on a protein called fibrin. The breakdown of fibrin (fibrinolysis) can increase under certain conditions, such as:Bacterial infectionsIntense exerciseLow blood sugarNot enough oxygen to tissuesIn 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, str