Find the age-adjusted D-dimer cut-off for patients over 50 and compare a result against it, with the standard 500 cut-off under 50.
No advanced options for this tool.
Comparison
How to use this tool
The adjustment only changes the cut-off above age 50.
In ng/mL FEU or mg/L FEU, matching your lab's units.
Below the cut-off supports exclusion only together with clinical probability assessment.
A D-dimer above the cut-off is not a diagnosis of clot — imaging and clinical assessment decide.
Formula & worked example
At age 65 the cut-off is 65 × 10 = 650 ng/mL FEU, so a result of 400 ng/mL is below it, while 700 ng/mL is at or above it. Under age 50 the cut-off stays at 500 ng/mL.
Limitations — read this before you rely on it
The age-adjusted rule is validated for suspected venous thromboembolism in adults, not for pregnancy, cancer, recent surgery, or D-dimer units reported as DDU (which need a different conversion). Assays differ. This tool is not medical advice — clot assessment must be done by a clinician.
Frequently asked questions
For patients over 50, the cut-off rises with age (age × 10 ng/mL FEU) instead of a flat 500, because D-dimer rises with age.
A flat 500 cut-off makes almost every older patient 'positive', so age adjustment restores the test's ability to exclude clots safely.
In the validated setting, combined with a low or intermediate clinical probability, yes — but never as a stand-alone home test.
Fibrinogen-equivalent units and D-dimer units — two ways of reporting the same assay. This tool uses FEU; DDU values are roughly half and must not be entered directly.
No. D-dimer testing is ordered by clinicians as part of a diagnostic pathway, not as self-assessment.