Specialist marker · Cardiac and clotting
A D-dimer blood test measures a protein fragment released when a blood clot breaks down, so it reflects how much clotting activity is going on in the body. A normal result is reassuring; a raised result is common and has many harmless causes, so it is never a clot diagnosis on its own. D-dimer is included in TrueVitals Signature (£799), read alongside platelets, hs-CRP and the cardiac markers.
If you think you have a clot now, do not wait for a test. A painful, swollen, warm calf, sudden breathlessness, chest pain or coughing blood need same-day care: call 999 or go to A&E for chest pain or breathlessness, or call NHS 111. A private screening panel is not the right route for these symptoms.
When the body forms a clot, it builds a mesh of a protein called fibrin. As the clot is later broken down, fragments called D-dimers are released into the blood. A D-dimer test counts those fragments, so it reflects clotting and clot breakdown happening anywhere in the body.
That makes it very sensitive but not specific: it tells you clotting activity is raised, not where or why. In hospitals it is used to help rule out a clot in people with a low clinical probability, never as a diagnosis by itself.
D-dimer is usually reported in mg/L FEU, with results below about 0.5 mg/L treated as normal. From age 50, many labs use an age-adjusted cut-off (age × 0.01 mg/L), because levels naturally rise with age. Your report uses your lab's own range and reads the result with your platelets, inflammation markers and history from your lifestyle quiz.
D-dimer is sensitive to how the sample is handled, so on a small number of samples the lab cannot report it. When that happens your report says so plainly and is assessed on the markers that were returned.
| Option | Includes it | Price | What else you get |
|---|---|---|---|
| TrueVitals Signature | Yes | £799 incl. draw | With troponin T, FABP-3, hs-CRP, ApoB, Lp(a), homocysteine and the rest of Signature's 45 specialist markers. |
| TrueVitals Ultimate | No | £399 | Not included. Ultimate has the full blood count, platelets and hs-CRP. |
| NHS | Only if a clot is suspected | Free | Used in A&E and urgent care with a clinical risk score, not as routine screening. |
TrueVitals prices checked 5 November 2026. Every TrueVitals report is clinician-reviewed. Pay in instalments with Klarna or Clearpay. Signature is drawn at one of 70 Randox Health clinics; Ultimate at one of 103 partner clinics or with a home visit.
D-dimer is a background marker, not a clot test you can book. A raised result in someone without symptoms is usually explained by age, recent injury or inflammation. Anything that needs follow-up is flagged in your report with plain next steps through your GP.
A private panel is a good way to get a baseline, understand a result in context and track it over time. It does not replace your GP for symptoms, and anything that needs follow-up is flagged in plain words in your report.
D-dimer on its own rarely tells the whole story. In TrueVitals panels it is reported with these related markers:
In hospital, a normal D-dimer alongside a low clinical probability score helps doctors rule out a clot. A private screening test is not a substitute for that assessment. If you have symptoms of a clot, seek urgent care rather than booking a test.
Anything that increases clot formation and breakdown: recent surgery or injury, infection, inflammation, pregnancy, older age, cancer and liver disease, as well as clots themselves. A mildly raised result is common and often harmless.
No. D-dimer is included in Signature. Ultimate includes the full blood count, platelets and hs-CRP.
No fasting is needed for D-dimer itself, but other markers in Signature are best measured fasted, so an overnight fast is advised.
How this page was written: by James Smillie, founder of TrueVitals, reviewed by the TrueVitals clinical review team, using NHS and laboratory reference sources. Ranges are typical values; your report uses your lab's own ranges. TrueVitals sells the panels named on this page, so we have stated plainly what this test cannot do. Last updated 5 November 2026.
Signature: 230 biomarkers including all 45 specialist markers: D-dimer, troponin T, homocysteine and more. £799 including the draw.
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