Fibrinolysis - primary or secondary
Primary fibrinolysis; Secondary fibrinolysis
Fibrinolysis is a normal body process. It prevents blood clots that occur naturally 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. This may cause severe bleeding.

Blood clotting normally occurs when there is damage to a blood vessel. Platelets immediately begin to adhere to the cut edges of the vessel and release chemicals to attract even more platelets. A platelet plug is formed, and the external bleeding stops. Next, small molecules, called clotting factors, cause strands of blood-borne materials, called fibrin, to stick together and seal the inside of the wound. Eventually, the cut blood vessel heals and the blood clot dissolves after a few days.

Blood clots (fibrin clots) are the clumps that result when blood coagulates.
Causes
Blood clots form on a protein called fibrin. The breakdown of fibrin (fibrinolysis) can be due to:
- Bacterial infections
- Cancer
- Intense exercise
- Not enough oxygen to tissues
Your health care provider may give you medicines to help blood clots break down more quickly. This may be done if a blood clot causes a heart attack.
References
Brummel-Ziedins K, Mann KG. Molecular basis of blood coagulation. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 126.
Schafer AI. Hemorrhagic disorders: disseminated intravascular coagulation, liver failure, and vitamin K deficiency. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 166.
Weitz JI. Hemostasis, thrombosis, fibrinolysis, and cardiovascular disease. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 95.
Version Info
Last reviewed on: 1/25/2022
Reviewed by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
