Lab Test: D-dimer Level
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- Measurement of plasma D-dimer, a product of fibrin degradation, for the evaluation of conditions that involve intravascular thrombosis
- 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.
- 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.
- 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.
- 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.
- 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.
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