Clinic appointment
D-Dimer Test
D-Dimer, a protein fragment released into the blood when a blood clot is being broken down.
- Doctor-reviewed results
- Laboratory analysis
- 1 to 2 working days from lab receipt
- No fasting required
What’s included
1 marker measured
D-dimer
A fragment released when the body breaks down a blood clot. Many everyday things raise it, so it only means something when a clinician reads it alongside your symptoms and examination. If you think you have a blood clot, such as a painful, swollen leg, ask for an urgent GP appointment or contact NHS 111. If you also feel short of breath or have chest pain, call 999.
Overview
D-dimer rises when a blood clot is being broken down, so doctors use it to help decide whether a clot is likely. A low result in someone assessed as low risk makes a clot unlikely; a raised result is common for many reasons and needs a scan to settle the question. It is a clinic blood test that a clinician has usually asked for as part of an assessment.
A result must be interpreted by a clinician alongside symptoms and clinical assessment; it does not rule out or confirm a blood clot on its own. This is not a substitute for emergency care: sudden leg swelling, chest pain or breathlessness means calling 999 or going to A&E, not booking a blood test.
Who this is for and who it isn’t
Who it’s for
- Adults aged 18 and over
- People whose clinician has asked for a D-dimer as part of an assessment
- Anyone following up a previous clot on medical advice
Who it isn’t for
- Sudden leg swelling, chest pain or breathlessness means 999 or A&E, not a blood test. D-dimer rises in pregnancy, after surgery, with infection, cancer and simply with age, so a raised result on its own does not mean a clot, and it is not a test to reassure yourself at home.
- Anyone with a new, severe or worsening symptom: contact your GP or call NHS 111. A test you buy today is not a substitute for being examined.
Common reasons people choose this test
- A clinician has asked for a D-dimer
- Follow-up after a previous clot under medical advice
These are reasons people choose to test, not signs that something is wrong. A result is one part of a picture your doctor puts together with your history and an examination.
What your result looks like
Every result is shown with the unit and the reference range exactly as the laboratory reported it, with the doctor’s note underneath.
- D-dimer▲ High
- Result
- 780 µg/L FEU
- Range
- <500
| Marker | Result | Units | Range | Flag |
|---|---|---|---|---|
| D-dimer | 780 | µg/L FEU | <500 | ▲ High |
Doctor’s note (example)
D-dimer is raised. It rises for many reasons, including infection, pregnancy and age, so it does not mean a clot; but it cannot exclude one either, and we would phone you the same day to arrange assessment.
Values above are examples. Your report shows your own results with the laboratory’s units and reference range for your age and sex, reviewed, signed and released by a GMC-registered doctor.
How it works
- You book your appointmentA trained clinician takes your sample at one of our London clinics. Nothing to do at home.
- The clinician takes your sampleA single clinic blood draw by a trained clinician
- The laboratory analyses itYour sample is processed for the measurements included in this test. Lab processing typically takes 1 to 2 working days from receipt of your sample.
- A doctor reviews and releases itA GMC-registered doctor reads every result and signs the report before it reaches you.
- Sample
- Clinic blood draw
- Preparation
- No fasting required
- Who it's for
- Any sex · ages 18+
How to prepare
What we can and can’t tell you
The reference range beside each result is the laboratory’s own. A result in range is not a clean bill of health and a result outside it is not a diagnosis. Most ranges cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one range. No test result replaces an examination or your own doctor’s judgement, and none of these panels is a cancer screening programme.
Read the full note
The reference range printed beside each of your results is the laboratory's own, and it is the range that applies to your result. We do not apply a second range of our own, and we do not tell you that a result the laboratory reported as normal is nonetheless too low or too high. If you see a claim elsewhere that your result ought to sit inside a narrower band than the one the laboratory printed, treat it with caution and ask your doctor.
Some assays cannot give an exact figure above or below a certain point, and those results are reported the way the laboratory sends them, for example as a value greater than a stated number. A result in range is not a clean bill of health, and a result outside a range is not a diagnosis: most reference ranges are set to cover about 95% of healthy people, so some healthy people fall just outside them. No blood test replaces an examination, a scan or your own doctor's judgement, and none of these panels is a screening programme for cancer.
If you have a symptom that is new, severe, or getting worse, contact your GP or NHS 111 rather than waiting for a test result. In an emergency call 999.
Frequently asked questions
What happens if it is raised?
The reviewing doctor contacts you and advises on urgent assessment, usually an ultrasound or CT scan, because the blood test alone cannot say whether a clot is present.
Do I need to fast?
No.
How long do results take?
The laboratory typically takes 1 to 2 working days from receiving your sample. This does not include kit delivery, sample collection or return postage. A doctor reviews your results before they are released.
Can I choose a home kit or a clinic?
This test is a clinic blood draw, as it needs a venous sample for accuracy. We arrange a convenient appointment for you.
Is a doctor involved?
Yes. Every result is reviewed by a GMC-registered doctor who signs it off and explains what it means and what to do next.
Is it confidential?
Your results are available through your secure patient portal. Our privacy policy explains how your information is handled and when it may be shared to provide your care.
What happens to my sample and results?
Your sample is analysed at a UKAS-accredited laboratory (ISO 15189). A GMC-registered doctor then reads your result and signs the report before it is released to your secure portal. The report shows your result with its unit and the laboratory's own reference range, and the doctor's note on what it means. If your result is raised, the reviewing doctor is alerted and we contact you by phone the same working day to advise on urgent assessment, which may mean A&E, an urgent GP appointment or a scan. A result in range cannot rule out a heart or clotting problem on its own. If you develop chest pain, sudden breathlessness, fainting or a swollen, painful leg at any point, call 999 or go to A&E rather than waiting for your result.
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