Fibrinogen Activity Test

Fibrinogen is a large protein made by your liver and found in your blood. It plays an essential role in stopping bleeding whenever a blood vessel is injured. When your body senses damage, fibrinogen is activated by an enzyme called thrombin. This transforms fibrinogen into fibrin, a sticky mesh that forms the main structure of a blood clot. Without enough fibrinogen, or if the fibrinogen does not work properly, your blood cannot clot effectively, leading to increased bleeding risk.

Fibrinogen also acts like a bridge between platelets, the tiny cells that clump together at injury sites. This platelet-fibrinogen connection helps form a strong initial plug to seal wounds even before the full clot develops.

Normally, blood fibrinogen levels range between about 200 and 400 milligrams per deciliter (mg/dL). A minimum of around 100 mg/dL is needed to maintain hemostasis, which means the body’s ability to stop bleeding. If levels fall below this, it can cause excessive bleeding, especially in surgeries, trauma, or childbirth. Conversely, if levels are abnormally high, it can contribute to unwanted blood clots that increase the risk of heart attacks or strokes.

Fibrinogen abnormalities can be congenital (inherited) or acquired (developing later in life). Common disorders include:

• Afibrinogenemia: No fibrinogen at all.
• Hypofibrinogenemia: Low levels of fibrinogen.
• Dysfibrinogenemia: Normal levels, but fibrinogen does not work correctly.
• Hypodysfibrinogenemia: Low and dysfunctional fibrinogen.

Several medical conditions affect fibrinogen activity:

• Massive trauma can use up fibrinogen rapidly, leading to dangerous bleeding.
• Disseminated intravascular coagulation (DIC), a severe condition, uses up clotting proteins including fibrinogen and causes widespread clotting and bleeding at the same time.
• Liver disease can impair fibrinogen production, making clotting problems worse.
• Obstetric hemorrhage (severe bleeding during childbirth) is strongly predicted by falling fibrinogen levels.
• Fibrinogen can be replaced when needed using cryoprecipitate, fresh frozen plasma, or fibrinogen concentrates. Concentrates are often preferred because they are fast-acting, safer, and avoid fluid overload.

Interestingly, fibrinogen does more than just help stop bleeding. In recent research, fibrinogen has been shown to play a role in inflammation and immune system activation. Deposits of fibrinogen in tissues, such as the brain in diseases like multiple sclerosis and Alzheimer’s, can promote scar formation and chronic inflammation.