D-Dimer Test
A blood test that helps rule out blood clots such as DVT and pulmonary embolism.
Quick Summary
To help rule out a blood clot when the risk is low.
D-dimer, a fragment released when clots break down.
No special preparation.
Overview
A normal D-dimer makes a clot unlikely.
A high result isn't specific: infections, pregnancy, surgery and older age also raise it, so scans are needed.
What It Measures
D-dimer
Clot breakdown product.
How It's Performed
- 01
Preparation
Usually no special preparation. Tell the staff about medicines you take.
- 02
Blood sample
A small amount of blood is taken from a vein in your arm with a thin needle.
- 03
Afterwards
Press on the spot for a minute. A small bruise is common; you can go back to normal activities.
Reference Ranges
Note: Normal ranges vary by laboratory. Consult your report for the specific reference used.
| Parameter | Typical Range (Adult) | Units |
|---|---|---|
| D-dimer | Below 0.5 | µg/mL FEU |
Interpreting Results & Next Steps
Discuss with Doctor
Age-adjusted cut-offs are used in older adults. Normal ranges differ between laboratories, ages and sexes; always use the range printed on your report and ask your doctor what your results mean.
If values are High:
A raised D-dimer may mean a clot and usually leads to a scan.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- D-Dimer Test(opens in a new tab) · MedlinePlus, US National Library of Medicine