What is the correlation of fibrin degradation products (FDPs) with Disseminated Intravascular Coagulation (DIC)?

Correlation of Fibrin Degradation Products with Disseminated Intravascular Coagulation (DIC)

Elevated fibrin degradation products (FDPs) strongly correlate with DIC and serve as a critical diagnostic marker, with increased FDP levels reflecting both coagulation activation and secondary fibrinolysis that characterize DIC pathophysiology. 1, 2

Diagnostic Value of FDPs in DIC

• FDP measurements play a key role in diagnosing DIC, with elevated levels being highly indicative of the condition 3
• FDPs are included in the International Society on Thrombosis and Haemostasis (ISTH) diagnostic criteria for overt DIC as one of the fibrin-related markers 1
• Semi-quantitative FDP tests using monoclonal antibodies demonstrate high sensitivity (88-100%) for DIC diagnosis 3
• The specificity of FDP tests for DIC diagnosis is approximately 97-98% when appropriate cutoff values are used 3

Relationship Between FDPs and DIC Pathophysiology

• FDPs reflect both coagulation activation and fibrinolysis status, which are the core pathophysiological processes in DIC 2
• In DIC, excessive thrombin generation leads to fibrin formation, followed by plasmin-mediated fibrinolysis that produces FDPs 4
• FDPs are produced when plasmin degrades both fibrinogen and fibrin, with cross-linked fibrin degradation being the predominant source in DIC 5
• Different types of FDPs can be detected in DIC, including D-dimer and fibrin degradation fragment E, which reflect secondary fibrinolysis activation 6

Cutoff Values and Quantification

• For DIC diagnosis using the ISTH overt DIC criteria, recommended FDP cutoff values are:
  • Moderate increase (2 points): 8.3 μg/mL
  • Strong increase (3 points): 42.0 μg/mL 7
• D-dimer, a specific type of FDP, has corresponding cutoff values of 2.4 μg/mL (2 points) and 22.0 μg/mL (3 points) 7
• A total score ≥5 on the ISTH criteria (which includes FDP/D-dimer values) confirms overt DIC 1

Clinical Significance and Monitoring

• Serial monitoring of FDP levels can help track DIC progression and response to treatment 6
• Increasing FDP levels accompanied by decreasing platelet count, fibrinogen, and prothrombin activity in consecutive measurements suggest worsening DIC 6
• FDP levels correlate with DIC severity and can help predict outcomes, with higher levels associated with increased mortality 7
• Different FDP reagents may have varying reactivity to fibrin degradation products, which can affect test results and interpretation 2

Limitations and Considerations

• FDPs can be elevated in other conditions besides DIC, including liver disease, malignancy, pregnancy complications, and deep venous thrombosis 5
• In liver disease, elevated FDPs may result from both increased production and decreased clearance 5
• The pattern of FDP elevation should be interpreted alongside other laboratory parameters (platelets, PT, fibrinogen) for accurate DIC diagnosis 1, 4
• Different types of FDP tests (plasma vs. serum, monoclonal vs. polyclonal antibodies) have varying sensitivities and specificities 3

Practical Application in DIC Management

• FDP measurement should be included in the initial evaluation of patients suspected of having DIC 1
• For optimal diagnostic accuracy, FDP testing should be combined with other parameters in the ISTH scoring system, including platelet count, PT prolongation, and fibrinogen levels 1
• In sepsis-induced coagulopathy (SIC), which may progress to DIC, FDP/D-dimer levels are important for risk stratification and management decisions 1
• Plasma-based FDP tests using monoclonal antibodies are preferred over serum-based tests using polyclonal antibodies due to higher sensitivity 3