Fibrinogen Activity, Clauss Test

The Fibrinogen Activity, Clauss Test is a diagnostic tool used to assess the functional activity of fibrinogen, a critical protein in blood clot formation. This test measures how effectively fibrinogen is converted into fibrin, which helps stabilize blood clots.

How the Clauss Test Works

• The test involves diluting platelet-poor plasma and adding a high concentration of thrombin to it.

• The time it takes for a clot to form is recorded. This clotting time is inversely proportional to the fibrinogen concentration in the plasma16.

• A calibration curve, based on reference plasma with known fibrinogen levels, is used to determine the patient's fibrinogen concentration67.

Purpose of the Test

The Clauss test is primarily used to:

• Diagnose bleeding disorders, such as hypofibrinogenemia (low fibrinogen levels) or dysfibrinogenemia (abnormal fibrinogen function)13.

• Monitor coagulation abnormalities, including those caused by disseminated intravascular coagulation (DIC) or liver disease35.

• Evaluate unexplained excessive bleeding or clotting58.

The fibrinogen activity test is utilized for numerous major therapeutic purposes:

Diagnosing inherited or acquired fibrinogen abnormalities
Evaluation of hemorrhagic
Monitoring disseminated intravascular coagulation (DIC)
Assessment of hepatic function
Monitoring thrombolytic treatment
Quantifying the risk of cardiovascular disease
A low amount of fibrinogen activity can be indicative of bleeding disorders, whereas high levels may imply an elevated risk of clotting or inflammation.

Normal and Abnormal Results

• Normal fibrinogen levels typically range from 200 to 400 mg/dL (2.0–4.0 g/L), though this can vary slightly between laboratories27.

• Low levels may indicate conditions like DIC, liver disease, or congenital fibrinogen deficiencies25.

• High levels can be associated with inflammation, pregnancy, or cardiovascular risks8.

Sample and Procedure

• Blood is collected in citrated tubes to prevent clotting before analysis.

• It is crucial that the sample is processed within 4 hours of collection to ensure accuracy1.

• No special preparation is required for the patient before the test3.

Clinical Applications

The Clauss test is invaluable for evaluating patients with:

• Symptoms of abnormal bleeding (e.g., frequent nosebleeds, gum bleeding, or gastrointestinal hemorrhage).

• Conditions involving excessive clot formation or breakdown (e.g., DIC or thrombosis) 56.

This test provides critical insights into clotting functionality and can guide treatment decisions for various coagulation disorders.

Interpretation of Results

Low values (<50 mg/dL) may suggest bleeding problems, liver illness, or DIC
High values (>700 mg/dL) can signify inflammation, infection, or increased clotting risk
Both low and high values require clinical correlation and perhaps further testing