Deep vein thrombosis laboratory tests: Difference between revisions
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==Overview== | ==Overview== | ||
D-dimer is used in the diagnosis of [[deep vein thrombosis]] among patients with low or unlikely probability of [[venous thromboembolism]].<ref name="pmid16403932">{{cite journal| author=Wells PS, Owen C, Doucette S, Fergusson D, Tran H| title=Does this patient have deep vein thrombosis? | journal=JAMA | year= 2006 | volume= 295 | issue= 2 | pages= 199-207 | pmid=16403932 | doi=10.1001/jama.295.2.199 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16403932 }} [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17213132 Review in: Evid Based Med. 2006 Aug;11(4):119] [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16813372 Review in: ACP J Club. 2006 Jul-Aug;145(1):24] </ref><ref name="pmid11453709">{{cite journal| author=Wells PS, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D et al.| title=Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. | journal=Ann Intern Med | year= 2001 | volume= 135 | issue= 2 | pages= 98-107 | pmid=11453709 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11453709 }} </ref> While 500 ng/mL has long been the most commonly used cut off value for abnormal D-dimer concentration, recent studies suggest the use of an age adjusted cut-off concentration of D-dimer. The age adjusted cut-off value of D-dimer is 500 ng/mL for subjects whose age is less than 50 years, and the age multiplied by 10 for subjects older than 50 years.<ref name="pmid22511491">{{cite journal| author=Douma RA, Tan M, Schutgens RE, Bates SM, Perrier A, Legnani C et al.| title=Using an age-dependent D-dimer cut-off value increases the number of older patients in whom deep vein thrombosis can be safely excluded. | journal=Haematologica | year= 2012 | volume= 97 | issue= 10 | pages= 1507-13 | pmid=22511491 | doi=10.3324/haematol.2011.060657 | pmc=PMC3487551 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22511491 }} </ref><ref name="pmid23645857">{{cite journal| author=Schouten HJ, Geersing GJ, Koek HL, Zuithoff NP, Janssen KJ, Douma RA et al.| title=Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis. | journal=BMJ | year= 2013 | volume= 346 | issue= | pages= f2492 | pmid=23645857 | doi=10.1136/bmj.f2492 | pmc=PMC3643284 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23645857 }} </ref><ref name="JAMA 2014"> Righini M, Van Es J, Den Exter PL, et al. Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism: The ADJUST-PE Study. JAMA. 2014;311(11):1117-1124. doi:10.1001/jama.2014.2135. </ref> | |||
==Laboratory Findings== | ==Laboratory Findings== | ||
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Overview
D-dimer is used in the diagnosis of deep vein thrombosis among patients with low or unlikely probability of venous thromboembolism.[1][2] While 500 ng/mL has long been the most commonly used cut off value for abnormal D-dimer concentration, recent studies suggest the use of an age adjusted cut-off concentration of D-dimer. The age adjusted cut-off value of D-dimer is 500 ng/mL for subjects whose age is less than 50 years, and the age multiplied by 10 for subjects older than 50 years.[3][4][5]
Laboratory Findings
D-Dimer
D-dimer is a cross-linked fibrin degradation product and a marker of endogenous fibrinolysis. In the setting of ongoing thrombosis, its levels should be elevated in the blood that makes it an excellent screening tool to rule out DVT. Interpretation may be improved by using age adjusted levels:[6]
- Patients less than 50 years old: normal D-dimer is less than 500 µg/L.
- In patients 50 years or older: normal D-dimer is adjusted to be age multiplied by 10.
Specificity and Sensitivity
A large number of D-dimer assays are available and may vary in-between hospitals. In a meta-analysis of 217 studies involving DVT patients, the sensitivities of the D-dimer enzyme-linked immunofluorescence assay (ELFA) (96%), micro plate enzyme-linked immunosorbent assay (94%), and latex quantitative assay (93%; PE 95%) were superior to the whole-blood D-dimer assay (83%), and latex qualitative assay (69%). Because of this, ELISA assays are termed as "highly sensitive" and whole blood D-dimer assays is "moderately sensitive". Thus, D-dimer has a high sensitivity (sNOUT) and low specificity (sPIN) for DVT. This means that D-dimer is a better test for "ruling out" DVT rather than "ruling in".
Elevated in Other Conditions
D-dimer can be elevated in following conditions, which should be kept in mind while assessing its validity in patients with suspected DVT:
- Malignancy
- Disseminated intravascular coagulation
- Elderly
- Infection
- Pregnancy
- Surgery/Trauma
- Inflammatory conditions
- Atrial fibrillation
- Stroke
Use in DVT Diagnosis
D-dimer is the "test of choice" in patients who are considered to be "low risk" according to pre-test probability. More information regarding the use of D-dimer in diagnosis of DVT can be found here. If D-dimer is elevated, then DVT should be confirmed with ultrasound.[7][8]
D-dimer is more useful if its negative rather than positive. It has a great negative predictive value in low to moderate risk patients of DVT.
Workup for Hypercoagulation
- Activated protein C resistance
- factor V Leiden mutation
- Protein C
- protein S, free and total.
- Antithrombin
- Lupus anticoagulant
- Anticardiolipin antibodies
- Plasma homocysteine values
References
- ↑ Wells PS, Owen C, Doucette S, Fergusson D, Tran H (2006). "Does this patient have deep vein thrombosis?". JAMA. 295 (2): 199–207. doi:10.1001/jama.295.2.199. PMID 16403932. Review in: Evid Based Med. 2006 Aug;11(4):119 Review in: ACP J Club. 2006 Jul-Aug;145(1):24
- ↑ Wells PS, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D; et al. (2001). "Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer". Ann Intern Med. 135 (2): 98–107. PMID 11453709.
- ↑ Douma RA, Tan M, Schutgens RE, Bates SM, Perrier A, Legnani C; et al. (2012). "Using an age-dependent D-dimer cut-off value increases the number of older patients in whom deep vein thrombosis can be safely excluded". Haematologica. 97 (10): 1507–13. doi:10.3324/haematol.2011.060657. PMC 3487551. PMID 22511491.
- ↑ Schouten HJ, Geersing GJ, Koek HL, Zuithoff NP, Janssen KJ, Douma RA; et al. (2013). "Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis". BMJ. 346: f2492. doi:10.1136/bmj.f2492. PMC 3643284. PMID 23645857.
- ↑ Righini M, Van Es J, Den Exter PL, et al. Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism: The ADJUST-PE Study. JAMA. 2014;311(11):1117-1124. doi:10.1001/jama.2014.2135.
- ↑ Righini M, Van Es J, Den Exter PL, Roy PM, Verschuren F, Ghuysen A; et al. (2014). "Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism: the ADJUST-PE study". JAMA. 311 (11): 1117–24. doi:10.1001/jama.2014.2135. PMID 24643601.
- ↑ Wells PS, Anderson DR, Rodger M; et al. (2003). "Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis". N. Engl. J. Med. 349 (13): 1227–35. doi:10.1056/NEJMoa023153. PMID 14507948.
- ↑ Bates SM, Kearon C, Crowther M; et al. (2003). "A diagnostic strategy involving a quantitative latex D-dimer assay reliably excludes deep venous thrombosis". Ann. Intern. Med. 138 (10): 787–94. PMID 12755550.