D-dimer

D-dimers are specific degradation products of cross-linked fibrin that are released when the endogenous fibrinolytic system attacks the fibrin matrix of fresh venous thromboemboli.

The absence of a raised concentration of D-dimer implies that there is no fresh thromboembolic material undergoing dissolution in the deep veins or in the pulmonary arterial tree.

There is evidence that a normal D-dimer assay result was useful for ruling out pulmonary embolism (PE) in patients with a low pretest probability of PE or a nondiagnostic V/Q scan. A d-dimer below a certain cut point rules out PE with a high predictive value, at least in patients with a low or moderate clinical probability (4)

Conditions in which there may be a raised D-dimer include:

• pulmonary embolism
• deep vein thrombosis
• disseminated intravascular coagulation
• postoperatively

More detailed information concerning other causes and factors affecting D-dimer levels is included in the linked item.

Notes:

• D-dimer levels and prediction of recurrent VTE
  • a systematic review was undertaken (5)
    • patients who had completed at least 3 months of anticoagulation for a first episode of unprovoked (idiopathic) VTE and after approximately 2 years of follow-up, a negative D-dimer result was associated with a 3.5% annual risk for recurrent disease, whereas a positive D-dimer result was associated with an 8.9% annual risk for recurrence

Reference:

1. Evidence Based Medicine (1999); 4 (3): 90.
2. Moser K (1994). Diagnosing pulmonary embolism. BMJ (309): 1525-6.
3. Ann Emerg Med 2002 Aug;40(2):133-44
4. Evidence Based Medicine (2002); 8(1):29.
5. Verhovsek M et al. D-dimer to predict recurrent disease after stopping anticoagulant therapy for unprovoked venous thromboembolism.Ann Intern Med. 2008 Oct 7;149(7):481-90