Fibrinogen is a protein found in blood plasma that plays a vital role in blood coagulation. Fibrinogen levels in the blood can be detected with the use of a blood test that can also be used to look at the levels of other clotting agents and substances in the blood. Abnormally high or low levels of fibrinogen can reveal a wide range of medical conditions, from a predisposition to stroke to a bleeding disorder.
This protein is produced by the liver. When the body needs blood to clot, a reaction is created between fibrinogen and thrombin, converting fibrinogen to fibrin, a fibrous substance that slowly sticks together to create a blood clot. Coagulation can occur remarkably quickly, especially at the site of a small injury. Once the clot has served its purpose, the body will break up the clot, or in the case of a clot outside the body, the clot will crust over and fall off.
Some people are born with a condition known as afibrinogenaemia, which means they don't have enough fibrinogen. These people tend to bleed freely and profusely from injuries, and are prone to bruising and internal bleeding. Fibrinogen levels can also contribute to thrombosis, in which the blood clots too much. Excessive clotting can cause strokes, heart attacks, and other health problems. It can also lead to disseminated intravascular coagulation (DIC), in which numerous small clots form throughout the body.
There are several reasons for a doctor to order a blood test to determine fibrinogen levels. If a patient appears to have some type of bleeding disorder, the blood test will give the doctor an idea of what the root of the problem might be. The test can also be used to monitor liver disease, a chronic condition that can cause changes in fibrinogen levels. These changes can be used as markers to indicate the appearance of complications or problems.
The normal range for fibrinogen is quite varied. Levels can fluctuate in an individual in response to things like blood transfusions and systemic injury, which can make it difficult to get a baseline. When laboratory results are sent to a physician for interpretation, these results generally include a "normal range" that provides levels for patients of similar age, height, and weight, corrected for gender differences. A physician may determine that an individual patient's apparently high or low levels are actually normal, given the patient's history and condition.