How this calculator works
The ADJUST-PE study used age x 10 µg/L FEU from age 50 onward, with a conventional 500 µg/L threshold for younger adults. ACEP also describes age x 5 ng/mL for DDU assays above age 50. DDU assays can have different fixed thresholds; for younger adults this tool uses the laboratory value you enter. The 230 ng/mL default comes from the cited HemosIL HS study. The calculation applies only within an appropriate adult, non-high clinical-probability PE pathway using a suitable assay. It cannot exclude PE by itself and is not a pregnancy pathway. The result is an estimate for information only and is not medical advice.
Formula
Above 50 years: FEU threshold (ng/mL) = age x 10; DDU threshold = age x 5. At 50 or younger: FEU 500 ng/mL, DDU laboratory fixed cut-off. 1 ng/mL = 1 µg/L; 1000 ng/mL = 1 mg/L = 1 µg/mL.
Worked example
At age 65 the threshold is 650 ng/mL FEU, or 0.65 mg/L FEU. For a DDU assay at age 80, it is 400 ng/mL DDU, or 0.4 mg/L DDU.
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Frequently asked questions
Are FEU and DDU interchangeable labels?
No. Confirm the assay calibration and its validated clinical pathway before interpreting a result.
Can I recover age from a fixed cut-off?
No. Many ages share the same fixed threshold, so the reverse mode only accepts adjusted thresholds implying age above 50.
Does a value under this threshold prove there is no clot?
No. Clinical probability, assay suitability and the diagnostic pathway determine whether a D-dimer result can be used to rule out PE.