Fibrin degradation product

D-dimer production.pdf

Fibrin Degradation Product (FDP) refers to fragments released into the blood after fibrin—a protein involved in blood clotting—is broken down. The process of fibrinolysis, which involves the breakdown of fibrin clots, leads to the production of FDPs. These products are significant in diagnosing and monitoring various medical conditions, including disseminated intravascular coagulation (DIC), deep vein thrombosis (DVT), and pulmonary embolism (PE).

Overview

Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is formed by the action of the enzyme thrombin on fibrinogen, a soluble plasma protein. Fibrin then assembles into a mesh that traps blood cells to form a stable blood clot, which is essential for stopping bleeding. However, to prevent clots from growing too large or forming inappropriately, the body must remove them once they have served their purpose. This is achieved through fibrinolysis, where plasmin, a serine protease, digests fibrin into smaller fragments known as fibrin degradation products.

Clinical Significance

FDP levels are measured in the blood to assess the fibrinolytic activity and coagulation status of a patient. Elevated levels of FDPs can indicate an increased breakdown of fibrin, suggesting an active or recent clotting and subsequent fibrinolytic process. This can be seen in conditions such as:

• Disseminated Intravascular Coagulation (DIC) - a severe condition characterized by the widespread activation of coagulation, leading to the formation of blood clots throughout the body's small vessels.
• Deep Vein Thrombosis (DVT) - the formation of a blood clot in a deep vein, usually in the legs.
• Pulmonary Embolism (PE) - a blockage in one of the pulmonary arteries in the lungs, usually caused by blood clots that travel to the lungs from the legs or, rarely, other parts of the body (DVT).

Measuring FDP levels, along with other markers such as D-dimer, helps in the diagnosis and management of these conditions. Elevated FDP levels alone, however, are not specific to any particular disorder and must be interpreted in the context of the patient's clinical presentation and other laboratory findings.

Laboratory Measurement

FDP levels are measured using various assays, including immunological techniques and enzyme-linked immunosorbent assays (ELISA). These tests are sensitive to the different fragments produced during fibrinolysis, allowing for the quantitative determination of FDPs in the blood.

Limitations

While FDP and D-dimer tests are valuable in diagnosing conditions associated with thrombosis and fibrinolysis, they have limitations. False positives can occur, especially in patients with liver disease, inflammation, or after surgery. Therefore, these tests should not be used in isolation for diagnostic purposes.

Conclusion

Fibrin degradation products are crucial markers for the assessment of coagulation and fibrinolytic activity in the body. Their measurement plays a significant role in diagnosing and managing conditions associated with abnormal clotting and fibrinolysis. However, the interpretation of FDP levels requires careful consideration of the overall clinical context and other diagnostic tests.