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Test Code D-Dimer D Dimer

Important Note

Tube must be properly filled.

Additional Codes

Cerner

NextGen

D-Dimer

D Dimer

Methodology

The STA®-Liatest D-Di test is an immuno-turbidmetric assay. D-dimer measurement is a photometric test based on the change in turbidity of a microparticle suspension. A suspension of latex microparticles coated with monoclonal antibodies for D-dimer is mixed with patient plasma. An antigen-antibody reaction occurs leading to agglutination of the latex particles which causes an increase in turbidity of the suspension, proportional to the concentration of D-dimer in the plasma. The increase in turbidity causes an increase in absorbance which is measured by photometry. The instrument automatically plots OD results on a standard curve and converts the results to µg/mL.

Patient Preparation

None

Collection Instructions

  • Sample collections must comply with the recommendations for hemostasis tests.
  • 3.2% sodium citrate tubes only.
  • Tube must be properly filled.
  • Centrifuge within 4 hours of collection.

Specimen Requirements

Preferred Volume

1 mL plasma

Minimum Volume

1 mL plasma

Container

3.2% sodium citrate tube (blue top), BD or Greiner Vacutainer tubes 

Stability

Specimens must be centrifuged and plasma removed within 4 hours of collection.

 

Plasma Storage:

  • 8 hours at 15-25⁰ C
  • 1 month at -20⁰ C (thaw once at 37⁰ C); double-spin to create platelet poor plasma.

Rejection Criteria
  • Clotted
  • Hemolyzed (refer to Limitations section)
  • Lipemic (refer to Limitations section)
  • Icteric (refer to Limitations section)
  • Expired collection tube
  • Under or Overfilled tube (blood/anticoagulant ratio must be 9:1; tube filled between 90-110 %)
  • Improperly mixed specimen

Result Reporting and Reference Values

Reference Range

0 – 0.41 µg/mL FEU

Clinical Exclusion Cutoff Value for DVT and PE

≤ 0.5 µg/mL FEU, for patients with low or moderate pretest probability scores*

Critical Ranges

None

*Pretest probability (PTP) scores are based on Wells’ model for low, moderate, or high risk.

Reflex Testing

None

Limitations

  • Cloudy plasmas may lead to an under-estimation of the D-dimer level.  The assay has been shown to be insensitive to triglycerides up to 500 mg/dL.
  • Over-estimation of D-dimer levels may occur in the following conditions:
    • Concentrations of FDP greater than 15 µg/mL
    • RF at a level > 50 IU/mL
    • The presence of anti-bovine and/or anti-mouse antibodies in certain subjects
  • The STA® Liatest® D-dimer is insensitive to the following substances:
    • Hemoglobin up to 200 mg/dl
    • Conjugated bilirubin up to 29 mg/dl
    • Unconjugated bilirubin up to 20 mg/dl
    • Unfractionated heparin up to 2 IU/mL
    • LMWH up to 2 anti-Xa IU/mL
    • Triglycerides up to 500 mg/dl
  • Patients with distal DVT may have normal D-dimer levels.
  • D-dimer assay should not be used in patients with high PTP (pretest probability) score.
  • D-dimer levels increase during pregnancy and with age.

Useful For

D-dimer molecules are the terminal product of fibrin degradation and are derived from the action of plasmin, a fibrinolytic enzyme, on a fibrin clot. Their presence in plasma is evidence that the fibrinolytic system is active in response to coagulation activation. D-dimer is useful as a negative predictor in the exclusion of deep vein thrombosis (DVT) and pulmonary embolism (PE), is helpful in the diagnosis and management of DIC (typically D-dimer increases during DIC), and is involved in the activation states of coagulation (i.e. increased levels of D-dimer have been reported in post-operative periods, cancers, bleeding, and severe infections where fibrin formation has occurred which subsequently leads to enhanced fibrinolysis, causing D-dimer production).