The biochemical structure, physiology and clinical significance of fibrinogen: a review

Fibrinogen is a plasma glycoprotein with a high-molecular weight, it plays a critical role in hemostasis and as a precursor to fibrin, which is the main clotting factor. Fibrinogen exerts several functions, not only blood coagulation, but also in tissue repair, vascular integrity, immune regulation, and inflammation. When exposed to thrombin, fibrinogen is converted into fibrin, which make a three-dimensional mesh to stabilize the platelet plug and stop bleeding. Fibrinogen also functions as a positive acute-phase reactant, so that it is highly released during inflammation, infection, and tissue injury. There is increasing evidence that fibrinogen plays a role in the pathophysiology several clinical conditions such as malignancies, metabolic disorders, chronic inflammatory states, cardiovascular disease, thrombotic diseases, and congenital and acquired bleeding disorders are also characterized by perturbations in the fibrinogen system. At the clinical level, fibrinogen levels have been commonly estimated in order to diagnose and monitor coagulation disorders, perioperative bleeding, trauma, and critical illness, whereas increased fibrinogen has become an independent marker of cardiovascular and inflammatory risk. This review is designed to summarize the current knowledge about the biochemistry, physiology, and clinical relevance of fibrinogen, with a focus on recent discoveries and novel concepts about fibrinogen as a biomarker and the mechanism of action in health and disease.