The Fibrinogen blood test is known by names such as Factor I, Fibrinogen Activity, Functional Fibrinogen, Fibrinogen Antigen, Plasma Fibrinogen, and Hypofibrinogenemia Test. This is usually done to determine the fibrinogen levels in the blood. Fibrinogen happens to be an essential protein that helps the blood to clot and this helps the body to heal wounds faster. The fibrinogen activity test is conducted to measure the function of the fibrinogen in the blood. The result of this test is reported as the protein concentration in the blood.