# D-dimer

D-dimer is a scrap left over when your body breaks down a blood clot. An enzyme called plasmin chops up stabilized fibrin, the clot's mesh. D-dimer is the debris. So it acts as a general sign that your clotting system has been active. Labs measure it by immunoturbidimetric or ELISA assays, in FEU or DDU units. Its main job is to rule out a clot (venous thromboembolism). A low value (often under 500 ng/mL FEU), plus a low pre-test risk, has a negative predictive value above 95%. In plain terms, a clot is very unlikely. The ADJUST-PE study (Righini 2014) set an age-adjusted cutoff for patients over 50: your age × 10 ng/mL FEU. That safely improves accuracy in older adults. But D-dimer also rises with age, pregnancy, inflammation, surgery, injury, cancer, sepsis, and severe liver or kidney disease. So a high value is non-specific. You must read it alongside imaging.

## Sources

- Righini M, Van Es J, Den Exter PL, et al.. (2014). Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism: the ADJUST-PE study. JAMA. https://doi.org/10.1001/jama.2014.2135
- Favresse J, Lippi G, Roy PM, et al.. (2018). D-dimer: Preanalytical, analytical, postanalytical variables, and clinical applications. Critical Reviews in Clinical Laboratory Sciences. https://doi.org/10.1080/10408363.2018.1529734

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_Canonical: https://longevity-germany.com/en/glossary/d-dimer · Part of Longevity Cities · Updated 2026-06-22_