Fibrinogen Activity, Clauss 

Alternate Test Name: Factor I

Description: A Fibrinogen Activity Clauss test is a blood test that measures the amount of active Fibrinogen in your blood to evaluate your blood’s ability to form clots.

Also Known As: Fibrinogen Activity Test, Factor 1 Assay Test, Cardiac Fibrinogen Test, Fibrinogen Test, Clotting factors Test

Collection Method: Blood Draw

Specimen Type: Whole Blood

Test Preparation: No preparation required

When is a Fibrinogen test ordered?

A fibrinogen activity test may be ordered by a doctor if someone:

When someone obtains a low result on a fibrinogen activity test, a fibrinogen antigen test may be used to establish whether the low result is due to insufficient or malfunctioning fibrinogen.

Coronary heart disease, myocardial infarction, and peripheral artery disease have all been linked to high fibrinogen levels. When a health practitioner wants to assess an individual's risk of developing cardiovascular disease, fibrinogen activity testing may be used in conjunction with other tests.

What does a Fibrinogen blood test measure?

Fibrinogen is a protein that is a coagulation factor in the production of blood clots. A fibrinogen activity test determines how well fibrinogen aids in the formation of a blood clot, whereas a fibrinogen antigen test determines the amount of fibrinogen in the blood.

Fibrinogen is produced in the liver, and is then delivered into the bloodstream along with many other coagulation factor proteins. Hemostasis stops bleeding at the site of injury when a blood vessel or body tissue is damaged. Platelets, small cell fragments, stick to and cluster at the site, triggering a coagulation cascade in which clotting components are activated one by one.

As the cascade develops, soluble fibrinogen turns into insoluble fibrin strands. At the wound site, a fibrin net is created by the crosslinking of these threads and stabilizes it. Together with the platelets, the fibrin net adheres to the area of injury and creates a solid blood clot. This barrier prevents more blood loss and is present while the injured area recovers.

There must be enough typically functioning platelets and coagulation factors for a stable clot to form. It can cause bleeding episodes and/or the creation of an inappropriate blood clot if there are defective factors or platelets, or if there are too few or too many of them. Hemostasis can be assessed using a variety of laboratory techniques, including fibrinogen assays.

Coagulation tests are now known to be based on what happens artificially in the test setting and so do not always reflect what happens in the body. The tests can, however, be used to assess individual components of the hemostasis system. The fibrinogen activity test measures the amount of soluble fibrinogen that is transformed into fibrin threads during the hemostatic process. The fibrinogen test bypasses the rest of the coagulation factors and concentrates on the function of fibrinogen after adding thrombin to the test sample.

A fibrinogen activity test determines how long it takes for a fibrin clot to form after a standard dose of thrombin is added to plasma. This test assesses the function of fibrinogen, specifically its capacity to convert into fibrin. The amount of active fibrinogen present directly correlates with the time it takes for a clot to develop. Prolonged clot formation periods can be caused by low levels of normal fibrinogen or by fibrinogen that is dysfunctional.

Acute phase reactants are a group of blood components that include fibrinogen. When conditions cause acute tissue inflammation or injury, blood levels of fibrinogen and other acute phase reactants rise dramatically. These acute phase reactants, including fibrinogen, can be tested to see how much inflammation is present in the body.

Lab tests often ordered with a Fibrinogen test:

Conditions where a Fibrinogen test is recommended:

Commonly Asked Questions:

How does my health care provider use a Fibrinogen test?

This test is designed to assess fibrinogen, a protein that is required for the production of blood clots. When an injury happens and bleeding occurs, the body goes through a sequence of actions to build a blood clot. One of the final phases is converting soluble fibrinogen into insoluble fibrin threads that crosslink to form a net that stabilizes and binds to the injured site until it heals.

A fibrinogen activity test assesses fibrinogen's function and capacity to convert to fibrin. It's utilized to:

Other cardiac risk markers, such as C-reactive protein, are sometimes used to assist in evaluating a person's overall risk of developing cardiovascular disease. However, because there are no direct treatments for increased levels, this application of the test has not achieved general adoption. Many health professionals, on the other hand, believe that measuring fibrinogen activity provides them with extra information that may drive them to be more aggressive in addressing those risk factors that they can control.

What do my fibrinogen activity test results mean?

The concentration of protein in the blood is reported as the result of a fibrinogen test. 

The presence of normal fibrinogen activity usually indicates that the blood clotting ability is normal.

Reduced or malfunctioning fibrinogen may be the cause of significantly reduced fibrinogen activity. Reduced fibrinogen activity and antigen levels can make it more difficult for the body to produce a stable blood clot.

Reduced production owing to a hereditary illness such as afibrinogenemia or hypofibrinogenemia, or a condition such as malnutrition or liver disease, can cause chronically low levels.

Acutely low levels are frequently associated with fibrinogen consumption, such as in disseminated intravascular coagulation and irregular fibrinolysis, which happens when the body is overly active in removing blood clots. Reduced fibrinogen levels can also occur as a result of quick, large-volume blood transfusions or in malnourished patients.

A ratio of the antigen test and the activity test is sometimes used by a doctor. This is to differentiate dysfibrinogenemia from hypofibrinogenemia.

Fibrinogen is an acute phase reactant, which means that it can rapidly rise in amounts in any situation that causes inflammation or tissue injury. Elevated fibrinogen concentrations aren't specific, which means they don't inform the doctor what's causing the problem or where it's happening. These increases in fibrinogen are usually just transitory, returning to normal after the underlying problem is treated. Elevated levels can be seen in the following ways:

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.