From the Guidelines
Elevated D-dimer levels and decreased fibrinogen levels are concerning for Disseminated Intravascular Coagulation (DIC) and require immediate attention to manage the underlying cause and prevent further complications, as recommended by the ISTH guidance on DIC 1.
Key Laboratory Markers
- D-dimer levels: often >2000 ng/mL in DIC
- Fibrinogen levels: <100 mg/dL in DIC
Management
- Treat the underlying cause (e.g., sepsis, trauma, or malignancy)
- Supportive care
- Possibly blood product replacement, such as:
- Cryoprecipitate or fibrinogen concentrate if fibrinogen is below 100 mg/dL with active bleeding
- Platelet transfusions for counts below 50,000/μL with bleeding
- Fresh frozen plasma for prolonged PT/PTT
Monitoring
- Continuous monitoring of coagulation parameters is essential, with repeat testing every 4-6 hours in acute cases, as suggested by the French working group on perioperative haemostasis (GIHP) and the French study group on thrombosis and haemostasis (GFHT) 1.
- Monitoring of D-dimer levels every 24-48 hours during the first 7-10 days in critically ill patients to assess thrombotic risk
- Monitoring of platelet count, prothrombin time, and fibrinogen level to diagnose heparin-induced thrombocytopaenia and DIC
Pathophysiology
- Widespread activation of coagulation leads to simultaneous clotting and bleeding as clotting factors and platelets are consumed
- This creates a paradoxical situation where D-dimer (a fibrin degradation product) increases while fibrinogen decreases, reflecting the accelerated clot formation and breakdown occurring throughout the vasculature, as noted in the study by Tang et al. 1.
From the Research
D-dimer and Fibrinogen Levels Concerning for DIC
- D-dimer and fibrinogen levels are important markers in the diagnosis of Disseminated Intravascular Coagulation (DIC) 2, 3, 4
- Elevated D-dimer levels and decreased fibrinogen levels can indicate the presence of DIC, as they suggest the activation of the coagulation and fibrinolytic systems 2, 4
- The determination of D-dimer, fibrin(ogen) split products, and soluble fibrin monomer can further support the diagnosis of DIC, although these tests are not specific for the condition 2
Clinical Significance of D-dimer and Fibrinogen Levels
- Decreasing fibrinogen levels and platelet counts can support the diagnosis of DIC, while elevated D-dimer levels can indicate the presence of thrombin and plasmin 2, 3
- Fibrinogen and D-dimer variances can have predictive value for mortality in patients with sepsis secondary to complications of DIC 4
- Anticoagulation therapy may be started following the diagnosis of DIC, despite the bleeding risks, particularly in patients with higher D-dimer levels (> 3.0 μg/mL) 4
Laboratory Tests and Diagnosis
- Laboratory tests, including D-dimer, fibrinogen, and platelet counts, are essential in confirming the clinical suspicion of DIC 2, 3
- The D-dimer assay is a valuable marker of activation of coagulation and fibrinolysis, and can be used to exclude the diagnosis of venous thromboembolism and to monitor other conditions in which the patient is at high risk of bleeding or thrombosis 5