*4.3.2.4. Fibrinogen (in plasma)*

Fibrinogen (Fbg), a precursor of fibrin, is also an acute-phase protein, which in coagulation cascade is the final substrate in the formation of a clot being converted to its insoluble fibrin form [217]. Fibrinogen belongs to the group of β-globulins and is present in the plasma. It is composed of three polypeptide chains linked by disulfide bridges and a glycoprotein [218]. Fibrinogen plays an important role in homeostatic processes, providing a substrate for fibrin formation. It is also involved in tissue reparation, and provides a matrix for the migration of inflammatory-related cells [219]. During an inflammatory reaction, fibrinogen can increase 2–3 folds, which may significantly increase blood viscosity and cause red cell aggregation, as well as may contribute to the growth of atherosclerotic plaques [220]. In human, studies showed an association between fibrinogen concentrations and subsequent cardiovascular disease risk, atherosclerosis, and acute thrombosis [221]. In cattle, fibrinogen has been used for many years to evaluate inflammatory and traumatic diseases, and is characterized by markedly increased synthesis in response to infection [222].
