Fibrinogen is a coagulation factor that is essential for blood clot formation. It is produced in the liver and has a half-life of three to five days, and decreased levels indicate an increased risk of blood clots leading to conditions like disseminated intravascular coagulation. Elevated levels of fibrinogen have also been linked to an increased risk of coronary heart disease. Two types of tests are available to evaluate fibrinogen, (1) a fibrinogen activity test that measures the rate of blood clotting and (2) a fibrinogen antigen test that measures the amount of fibrinogen in the blood.