Deep vein thrombosis laboratory tests: Difference between revisions
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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 | 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". | 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". | ||
Revision as of 17:21, 1 February 2013
Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2] ; Kashish Goel, M.D.; Assistant Editor(s)-In-Chief: Justine Cadet
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Deep Vein Thrombosis Microchapters |
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Diagnosis |
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Treatment |
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Special Scenario |
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Trials |
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Case Studies |
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Deep vein thrombosis laboratory tests On the Web |
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Risk calculators and risk factors for Deep vein thrombosis laboratory tests |
Overview
The lifetime incidence of DVT ranges from 2-5% in the general population. It accounts for a large number of ER visits and puts the patient at-risk for a life-threatening pulmonary embolism. The use of D-dimer after assessment of pre-test probability has been widely validated now and has led to a significant reduction in unnecessary procedures in the ER and hospital settings. This chapter will review the role of D-dimer in diagnosis of DVT. For a detailed discussion on D-dimer, please visit D-dimer.
Laboratory Findings
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
D-dimer
D-dmer 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.
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.[1][2]
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.
References
- ↑ 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.