D-dimer Tests

D-dimer tests are used to check for blood clotting problems. You may have a blood sample drawn from a vein in your arm to get tested.

Results:

• A normal test result is negative, which means there’re probably no problems with blood clotting.
• A positive result may mean:
  • there is blood clot (thrombus), but it does not tell the location or the reason.
  • Or, it may be caused by other conditions such as pregnancy, infection, liver disease, recent surgery or trauma, heart attack and aging.
• When monitoring disseminated intravascular coagulation (DIC) treatment,
  • decreasing levels mean the treatment is effective;
  • increasing levels mean the treatment is not working.

“Negative” means D-dimer level is below a predetermined cut-off threshold. Some labs gives out the value. In this case:

• a normal value is < or =500 ng/mL Fibrinogen Equivalent Units (FEU)
• D-dimer values < or =500 ng/mL FEU may be used in conjunction with clinical pretest probability to exclude deep vein thrombosis (DVT) and pulmonary embolism (PE).

As D-dimer is a sensitive test but has a poor specificity, it is only used to rule out deep vein thrombosis (DVT), not to confirm a diagnosis.

Keywords: D-dimer, Fibrin Degradation Fragment, Fragment D-dimer