D-dimer
In medicine, D-dimer is a fibrin degradation product after coagulation. It may be elevated in patients with pulmonary embolism or deep venous thrombosis.
Immunologic tests for d-dimer are generally use immunoassays such as enzyme-linked immunosorbent assay or serologic tests such as agglutination tests. The immunoassays (more specifically, enzyme-linked immunosorbent assay) tend to be more sensitive.[1]
In interpretation of the d-dimer, for patients over age 50 a value of ageX10 may be abnormal.[2]
| sensitivity | specificity | |
|---|---|---|
| Immunoassays | ||
| Elisa such as VIDAS™ | 95%[1] 96%[3] |
44%[1] 39%[3] |
| Agglutination tests | ||
| Latex agglutination such as Tinaquant™ | 89%[1] 96%[3] |
45%[1] 43%[3] |
| Whole blood hemagglutination test such as SimpliRED™ | 78%[1] 87%[3] |
74%[1] 66%[3] |
Using D-dimer to determine duration of anticoagulation treatment
An abnormal D-dimer level at the end of treatment might signal the need for continued anticoagulation with warfarin among patients with embolism and thrombosis such as a first unprovoked pulmonary embolism. If the D-dimer is abnormal, anticoaguation should be continued, if the D-dimer is normal, the duration of treatment is uncertain.[4] In an observation study that collected the D-dimer before stopping anticoagulation, the D-dimer was not as predictive.[5]
Screening for deep venous thrombosis
Especially in emergency medicine, it is both fast and economical to use D-dimer to rule out deep venous thrombosis, without going directly to the more time-consuming and expensive Doppler ultrasonography. " Five hundred thirty patients were randomly assigned to the control group, and 566 to the D-dimer group. The overall prevalence of deep-vein thrombosis or pulmonary embolism was 15.7 percent. Among patients for whom deep-vein thrombosis had been ruled out by the initial diagnostic strategy, there were two confirmed venous thromboembolic events in the D-dimer group (0.4 percent; 95 percent confidence interval, 0.05 to 1.5 percent) and six events in the control group (1.4 percent; 95 percent confidence interval, 0.5 to 2.9 percent; P=0.16) during three months of follow-up. The use of D-dimer testing resulted in a significant reduction in the use of ultrasonography, from a mean of 1.34 tests per patient in the control group to 0.78 in the D-dimer group (P=0.008). Two hundred eighteen patients (39 percent) in the D-dimer group did not require ultrasound imaging."[6]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Stein PD, Hull RD, Patel KC, et al. (April 2004). "D-dimer for the exclusion of acute venous thrombosis and pulmonary embolism: a systematic review". Ann. Intern. Med. 140 (8): 589–602. PMID 15096330. [e]
- ↑ Douma RA, le Gal G, Söhne M, Righini M, Kamphuisen PW, Perrier A et al. (2010). "Potential of an age adjusted D-dimer cut-off value to improve the exclusion of pulmonary embolism in older patients: a retrospective analysis of three large cohorts.". BMJ 340: c1475. DOI:10.1136/bmj.c1475. PMID 20354012. Research Blogging.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Di Nisio M, Squizzato A, Rutjes AW, Büller HR, Zwinderman AH, Bossuyt PM (February 2007). "Diagnostic accuracy of D-dimer test for exclusion of venous thromboembolism: a systematic review". J. Thromb. Haemost. 5 (2): 296–304. DOI:10.1111/j.1538-7836.2007.02328.x. PMID 17155963. Research Blogging.
- ↑ Palareti G, Cosmi B, Legnani C, et al (2006). "D-dimer testing to determine the duration of anticoagulation therapy". N. Engl. J. Med. 355 (17): 1780-9. DOI:10.1056/NEJMoa054444. PMID 17065639. Research Blogging.
- ↑ Rodger MA, Kahn SR, Wells PS, Anderson DA, Chagnon I, Le Gal G, et al. Identifying unprovoked thromboembolism patients at low risk for recurrence who can discontinue anticoagulant therapy. CMAJ. 2008 Aug 26;179(5):417-426.
- ↑ Wells PS et al. (September 25, 2003), "Evaluation of D-Dimer in the Diagnosis of Suspected Deep-Vein Thrombosis", New England Journal of Medicine 3499 (13): 1227-1235