Not medically reviewed
Coagulation
D-dimer
Not medically reviewed · Content last updated · 1 min read ·
This is the date the draft was written, not a medical review date.
D-dimer is a fibrin degradation product indicating activation of coagulation and fibrinolysis. It has a high negative predictive value to help exclude venous thromboembolism when pre-test probability is low or moderate.
Reference interval
| Conventional (ng/mL FEU) | SI (mg/L FEU) | |
|---|---|---|
| Adults | < 500 (upper limit) ng/mL FEU | < 0.5 (upper limit) mg/L FEU |
Specimen: Citrated plasma · Conventional × 0.001 = SI
Causes of high values
Venous thromboembolism, DIC, recent surgery or trauma, malignancy, infection and sepsis, pregnancy, advanced age, aortic dissection and acute coronary syndromes. It is non-specific and a raised value does not confirm thrombosis.
Causes of low values
Not applicable: low values are the normal finding and a negative result (below the assay cut-off) argues against thrombosis in appropriate pre-test probability categories.
Pre-analytical and method notes
Units differ by laboratory: fibrinogen equivalent units (FEU) versus D-dimer units (DDU, about half of FEU), and ng/mL versus mg/L (500 ng/mL FEU = 0.5 mg/L FEU). The conventional cut-off is about 500 ng/mL FEU, but cut-offs are assay-specific; age-adjusted cut-offs (age x 10 ng/mL FEU above 50 years) are used in many protocols. Use only with a validated clinical probability score and follow local guidelines.
References
- Rifai N, Horvath AR, Wittwer CT. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Elsevier, 6th edition (2018) — Tier 3 (textbook)
- Loscalzo J, et al.. Harrison's Principles of Internal Medicine. McGraw-Hill, 21st edition (2022) — Tier 3 (textbook)
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. Elsevier — Tier 3 (textbook)
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