During plasma coagulation soluble fibrin is generated. By degradation of cross-linked fibrin, characteristic products called D-dimers are released. Increased D-dimer levels indicate the activation of coagulation and fibrinolysis processes. Low levels of D-dimer are mainly used to exclude venous thromboembolism (VTE) such as deep vein thrombosis of the leg (DVT) and pulmonary embolism (PE).
Diagnostic value of D-dimer
- Determination of D-dimer can be used to exclude a suspected DVT or PE with levels below a specific cutoff value
- Since neither a reference method nor reference material are available, clinical studies are mandatory to define an assay-specific cut-off and calibrator values
- Several studies support the use of a cutoff value of 0.5 FEU (fibrinogen equivalent unit) µg/L
- If D-dimer levels are above the cutoff value imaging techniques as sonograhpy or phlebography are mandatory for a definitive diagnosis of VTE
- Specificity for DVT is variable and patient population dependent; adjusted cutoffs were suggested for e.g. elderly patients or for individuals with cancer