Fibrinogen

A coagulation protein that, together with thrombocytes, is responsible for part of the coagulation functionality of the human body. It is a high-molecular fibre protein, precursor of the blood coagulation protein fibrin, which is produced by the action of thrombin from fibrinogen.

Fibrinogen is the factor I of blood clotting. It is a soluble protein, a glycoprotein, and migrates in electrophoresis between β and γ globulins. It can also be precipitated with ethanol, ether, ammonium sulfate and coagulates under the action of heat.

Fibrinogen is formed in the liver and is rapidly converted (biological half-life about 5 days); occurs mainly in plasma (2-4.5 g/l) and about 20% outside the blood (in interstitium, exudates, etc.). Fibrinogen is also used therapeutically.

The serum concentration may be abnormally elevated (hyperfibrinogenemia), e.g. - as an acute phase protein - in infection, tumors, or reduced, e.g. in severe liver damage.

High fibrinogen concentrations appear to be a risk factor for cardiovascular and cerebrovascular diseases.