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Lab Test: D-dimer Level

    Lab Test
    • D-dimer
    Description
    • Measurement of plasma D-dimer, a product of fibrin degradation, for the evaluation of conditions that involve intravascular thrombosis
    Reference Range
    • Adults:  < 0.5 mcg/mL (< 0.5 mg/L)
    Indications & Uses
    • Suspected acute aortic dissection (AD)- D-dimer is the only known lab marker for AD for which a rapid assay is available.  D-dimer levels appear to be higher earlier I the course of the disease. 
    • Suspected acute coronary syndrome (ACS) - the low positive and negative predictive values of a D-dimer level in the setting of ACS make it difficult to draw any conclusions from either an elevated or a normal measurement.  There is some evidence to suggest that an elevated D-dimer in the setting of a normal ECG and normal cardiac enzymes should heighten concern for recurrent events. 
    • Suspected acute deep venous thrombosis (DVT) - in outpatients with a low pretest probability for lower-extremity DVT, the following tests can be used to exclude DVT:  a negative quantitative D-dimer assay (turbidimetric of ELISA) for exclusion of proximal and distal lower-extremity DVT, a negative whole blood cell qualitative D-dimer assay in conjunction with a Wells' scoring system for exclusion of proximal and distal DVT, or a negative whole blood D-dimer assay for exclusion of proximal lower-extremity DVT.  A negative D-dimer cannot exclude DVT in patients with a moderate or high pretest probability. 
    • Suspected acute pulmonary embolism (PE) - in emergency department patients with a low pretest probability of PE, a negative ELISA or turbidimetric D-dimer assay or a negative whole blood cell qualitative D-dimer assay in conjunction with a wells score of 2 or less is sufficient to exclude PE.
    • Suspected disseminated intravascular coagulation (DIC) - an elevated D-dimer level is suggestive of, though not conclusive for, DIC.  A normal D-dimer level has a high negative predictive value for DIC. 
    • Suspected preeclampsia - D-dimer assay is an early screen for coagulation abnormalities in women with a preeclamptic coagulopathy.
    Clinical Application
    • D-dimer is a fibrin degradation fragment that is made through lysis of cross-linked (D-dimerized) fibrin.  As plasmin acts on the fibrin polymer clot, fibrin degradation products and D-dimer are produced.  The D-dimer assay provides a highly specific measurement of the amount of fibrin degradation that occurs.  Normal plasma does not have detectable amounts of fragment D-dimer. 
    • The D-dimer can be tested by immunoturbidimetric methods or latex quantitative/qualitative assay.  
    • Results increased in:
      • Trauma, cancer, infection, pregnancy, increased age, decreased renal function, liver disease, burns, stroke/cerebrovascular disease, peripheral vascular disease, surgery, sickle cell anemia with or without vasoocclusive crisis, DIC, primary fibrinolysis, during thrombolytic or defibrination therapy, deep vein thrombosis, pulmonary embolism, or arterial thromboembolism.
    Related Tests
    • Prothrombin time (PT) - used to evaluate the adequacy of the extrinsic system and common pathway in the clotting mechanism.
    • Coagulating factor concentration - quantitative measurement of specific coagulation factors
    • Partial thromboplastin tine, activated (aPTT) - used to evaluate the intrinsic system and the common pathway of clot formation.  It is most commonly used to monitor heparin therapy.
    Drug-Lab Interactions
    • The D-dimer level may be decreased in lipemic patients.
    • The presence of rheumatoid factor at a level > 50 IU/mL may lead to increased levels of
    • D-dimer.
    Test Tube Needed
    • Blue top tube
    Procedure
    • Obtain plasma in sodium citrate tube
    • Collect a venous blood sample
    • Apply pressure or a pressure dressing to the venipuncture site and assess the site for bleeding.  If the patient is receiving anticoagulants or has coagulopathies, remember that the bleeding time will be increased.
    Storage and Handling
    • Store at room temperature for 8 hours or at -20°C for up to 6 months.
    What To Tell Patient Before & After
    • Explain the procedure to the patient. 
    • Tell the patient that no fasting is required.
    References
    • LaGow B et al., eds. PDR Lab Advisor. A Comprehensive Point-of-Care Guide for Over 600 Lab Tests.  First ed. Montvale, NJ: Thomson PDR; 2007.
    • Pagana K, Pagana TJ eds. Mosby's Manual of Diagnostic and Laboratory Tests. 5th Ed.  St. Louis, Missouri. 2014.

MESH Terms & Keywords

  • D-dimer