fibrinogeeni

Fibrinogeeni, known in English as fibrinogen, is a soluble plasma glycoprotein produced by the liver and circulating in blood at approximately 2–4 g/L. It is the precursor of fibrin, the main structural component of a blood clot, and plays a central role in hemostasis by supporting coagulation and platelet aggregation.

Fibrinogen is a large protein with a molecular weight around 340 kDa, composed of two identical sets of three polypeptide chains (Aα, Bβ, and γ). In blood, thrombin cleaves specific fibrinopeptides from the Aα and Bβ chains, producing insoluble fibrin monomers that polymerize to form a fibrin network. Factor XIIIa then crosslinks the network, stabilizing the clot. Fibrinogen also serves as a ligand for platelet aggregation through the GPIIb/IIIa receptor, helping to bridge platelets during clot formation.

Clinical significance: Fibrinogen is a positive acute-phase reactant, with levels rising in inflammation, infection, pregnancy, and with estrogen therapy. Conversely, levels can fall in liver disease, widespread coagulation activation such as disseminated intravascular coagulation (DIC), and in inherited disorders like afibrinogenemia or dysfibrinogenemia. Abnormal fibrinogen levels or function can lead to bleeding or thrombotic complications. Measurement is commonly performed by Clauss assays (functional activity) or antigen-based immunoassays.

Genetics and treatment: The fibrinogen molecule is encoded by three genes—FGA, FGB, and FGG. Inherited deficiencies can be treated with fibrinogen replacement therapy, such as fibrinogen concentrate or cryoprecipitate, depending on clinical context and available products.