Fibrinogen, also known as factor I, is a critical blood clotting protein produced by the liver that is essential for normal hemostasis. This test measures the amount of fibrinogen antigen in the blood, which helps diagnose various bleeding and clotting disorders. Fibrinogen deficiency can be congenital (inherited) or acquired due to liver disease, kidney disease, or conditions like disseminated intravascular coagulation (DIC). Low fibrinogen levels can cause excessive bleeding, while the test is also used to diagnose dysfibrinogenemia, a condition where fibrinogen is present but functionally defective. This test is commonly ordered when participant have unexplained bleeding, abnormal clotting test results, or when monitoring the effectiveness of thrombolytic therapy. Early detection of fibrinogen abnormalities is important for preventing serious bleeding complications and managing clotting disorders effectively.