Coagulation laboratory tests
D-dimer / Dimerized plasmin fragment D

Author: Jeremy Parsons, M.D. (see Authors page)

Revised: 9 May 2016, last major update June 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: D-dimer / Dimerized plasmin fragment D

Cite this page: D-dimer / dimerized plasmin fragment D. website. Accessed October 22nd, 2016.
Definition / General
  • Marker of ongoing procoagulant activity
  • Fibrin degradation products (fibrin split products) that are formed only by plasmin degradation of fibrin, not by plasmin degradation of intact fibrinogen, thus indicating that fibrin has been formed
  • D-regions of fibrinogen are crosslinked by factor XIII after the fibrin clot is formed
  • Plasmin cannot cleave the bond between the D-regions, so dimers are also found when a clot is broken down
  • Normal plasma level is probably due to physiologic clotting activity

  • Specimen:
    • Usually plasma with citrate anticoagulant
    • Values < 0.5 mg/L with quantitative ELISA assays have good negative predictive value for thromboembolic disorders
    • Other values are not predictive (Arch Pathol Lab Med 2004;128:519)

  • Suggested guidelines for D-dimer testing to rule out pulmonary emboli in patients with low clinical suspicion (if moderate or high clinical suspicion, should do imaging studies):
    • Age < 70 years, and no unexplained hypoxemia, unilateral leg swelling, recent surgery, hemoptysis, pregnancy or prolonged duration of symptoms (Acad Emerg Med 2005;12:20)
    • Elevated levels are sensitive but not specific for DIC
    • Elevated levels after completion of oral anticoagulation are associated with venous thromboemboli

  • LIA assay:
    • Mix patient plasma with latex particles coated with monoclonal anti-D-dimers or fibrin degradation product antibodies
    • Detect agglutination with coagulation analyzer and semiquantitate with dilutions
    • Although this is called a Latex ImmunoAssay, it differs from the qualitative latex agglutination assay that is NOT predictive of pulmonary emboli

  • ELISA method:
    • Also available

  • False positives:
    • Recent surgery
    • HIV+ Castlemans disease due to interference from monoclonal gammopathy (Arch Pathol Lab Med 2004;128:328)
    • High rheumatoid factor
    • Liver disease
    • Cancer patients
    • Pregnancy

  • Note: Some platforms use fibrinogen equivalent units, which are 50% the numerical value of D-dimer units
Clinical Images

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Fibrin split products / D-dimer