Fibrinogen is a soluble glycoprotein found in blood plasma that plays a critical role in the blood clotting (coagulation) process. It is synthesized in the liver and circulates in the bloodstream as an inactive precursor. When blood vessels are injured, the coagulation cascade is initiated, leading to the conversion of fibrinogen to its active form, fibrin. This conversion is mediated by the enzyme thrombin.

Fibrin forms a mesh-like structure that, together with platelets, creates a stable blood clot at the site of injury. This clot helps to prevent excessive bleeding and allows the healing process to begin. After the tissue has healed, the clot is broken down and removed by a process called fibrinolysis.

Abnormal fibrinogen levels can be associated with various medical conditions:

1. Low fibrinogen levels (hypofibrinogenemia): This condition can be caused by liver disease, malnutrition, or inherited disorders. Low fibrinogen levels can lead to an increased risk of bleeding, as the blood clotting process is impaired.
2. High fibrinogen levels (hyperfibrinogenemia): Elevated fibrinogen levels can be observed in inflammatory conditions, infections, cancer, or as a response to stress. High fibrinogen levels can increase the risk of blood clot formation (thrombosis), which can lead to conditions such as deep vein thrombosis (DVT) or stroke.

Fibrinogen levels can be measured as part of a coagulation profile, which also includes tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). These tests help clinicians diagnose and monitor bleeding disorders, assess the risk of thrombosis, and manage anticoagulant therapy.