What is the role of D-dimer and fibrin degradation product (FDP) tests in the workup of disseminated intravascular coagulation (DIC)?

Updated: Dec 06, 2020
  • Author: Marcel M Levi, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Fibrinolysis is an important component of DIC; thus, there will be evidence of fibrin breakdown, such as elevated levels D-dimer and FDPs. D-dimer elevation means that thrombin has proteolyzed fibrinogen to form fibrin that has been cross-linked by thrombin-activated factor XIIIa. When fibrin becomes cross-linked insoluble, a unique D-D domain neoepitope forms. This cross-linked insoluble fibrin is then proteolyzed uniquely by plasmin to liberate the soluble D-D dimer. Thus, the D-dimer measures prior thrombin and plasmin formation. On the other hand, FDPs only inform that plasmin has been formed and it cleaved soluble fibrinogen, fibrin, or insoluble cross-linked fibrin. D-dimer is the better test for DIC.

Accordingly, testing for D-dimer or FDPs may be helpful for differentiating DIC from other conditions that may be associated with a low platelet count and prolonged clotting times, such as chronic liver disease. Most laboratories have an operational test for D-dimer. In the United States, FDPs are not used as often.

D-dimer or FDPs may be detected by means of specific enzyme-linked immunosorbent assay (ELISA) or latex agglutination assay, allowing rapid and bedside determination in emergency cases. However, some of the available assays for FDPs cross-react with fibrinogen degradation products, and this cross-reactivity may cause spuriously high results. The specificity of high levels of D-dimer and FDPs is therefore limited, and many other conditions (eg, venous thromboembolism, trauma, inflammation, and recent surgery) may be associated with elevated FDP levels. [16, 63]

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