Key takeaways
- ESR (erythrocyte sedimentation rate) is a general marker of inflammation somewhere in the body, but it does not say where.
- At Blood London, an ESR test costs £43.75 plus the £50 blood draw, with results back in 1 day.
- ESR tends to rise with age and with anaemia, independent of inflammation, so a result is always read in context.
- ESR changes more slowly than other inflammation markers such as CRP, both to rise and to settle again.
- A raised ESR on its own is not a diagnosis; it is a prompt for a doctor to look for a cause alongside your symptoms.
- No fasting is needed for an ESR test.
ESR measures how quickly red blood cells settle to the bottom of a sample tube over an hour, which happens faster when certain proteins linked to inflammation are raised in your blood. It is a general, non-specific marker rather than a test for one condition. You can book an ESR blood test at Blood London without a GP referral.
Book an ESR blood test at 117a Harley Street: £43.75 plus the £50 blood draw, results in 1 day.
What does the ESR test actually measure?
ESR measures how far red blood cells fall through plasma in a vertical tube over one hour. When inflammation is present, certain proteins in the blood make red cells clump together and settle faster, so a higher ESR broadly reflects more inflammation somewhere in the body. It is one of the oldest blood tests still in routine use, valued precisely because it is simple, cheap and widely available, even though it cannot say what is causing the inflammation or where it is.
What can cause a raised ESR?
A raised ESR can be caused by a wide range of things, from a minor infection to chronic inflammatory conditions, and by factors that have nothing to do with illness at all. ESR rises with age, tends to run higher in women than men, and is also raised by anaemia, pregnancy and obesity, independent of any inflammatory process. Because it is such a general marker, a raised ESR on its own does not point to a specific diagnosis; it is more useful as a prompt to look further, or to track how a known inflammatory condition is behaving over time.
How is ESR different from CRP?
| Feature | ESR | CRP |
|---|---|---|
| What it reflects | Red cell settling rate, affected by inflammation-related proteins | Direct measurement of a protein made by the liver in response to inflammation |
| Speed of change | Rises over days and can take weeks to settle | Rises and falls quickly, over hours to days |
| Affected by age or anaemia | Yes, independently of inflammation | Less affected by age or anaemia |
| Typical use | Monitoring a known condition over time | Picking up or tracking a more acute change |
At Blood London, CRP can be booked alongside ESR when a doctor wants both a fast-changing and a slow-changing marker of inflammation (£70 plus the £50 blood draw, results in 1 day). Our guide to what a CRP result means covers that test in more detail.
Why does ESR change so slowly?
ESR changes slowly because it depends on proteins that themselves take time to rise and fall in the blood, and because the red cell settling process it measures is an indirect effect of those proteins rather than a direct count of them. This means ESR can stay raised for some time after an infection has cleared, and it can lag behind how someone is actually feeling. It is one reason ESR is often used to track a chronic or ongoing condition over weeks or months, rather than to catch a sudden change from one day to the next.
What are the plain, everyday uses of an ESR test?
ESR is typically used to support the assessment of unexplained symptoms such as persistent fatigue, joint pain or stiffness, or unexplained weight loss, and to monitor a condition that is already being managed, where a rising or falling trend over time matters more than any single result. It is rarely, if ever, used as a stand-alone test to diagnose a specific condition, and a doctor will usually order it alongside a full blood count and other relevant tests rather than in isolation.
Some symptoms need a doctor sooner. If you are over 50 and have a new headache, scalp tenderness, jaw pain when chewing or any change in your vision, see a doctor the same day, as this can be a sign of giant cell arteritis, which needs urgent treatment. Unexplained weight loss, night sweats or persistent bone pain also mean seeing a doctor promptly.
How testing works at Blood London
An ESR test costs £43.75 plus the £50 blood draw, with results usually back within 1 day. The Haematology Profile pairs a full blood count with ESR for £75 plus the £50 blood draw, also with results in 1 day, giving a broader starting picture in one visit. No fasting is needed. As with all our private blood tests in London, you can walk in or book online at 117a Harley Street, seven days a week, with no GP referral needed, and your results are sent to you by email.
Book an ESR blood test at 117a Harley Street: £43.75 plus the £50 blood draw, results in 1 day. Start your booking.
Frequently asked questions
Does a raised ESR mean I have an infection?
Not necessarily. A raised ESR reflects inflammation somewhere in the body, which can be caused by infection, but also by chronic conditions, anaemia, age or pregnancy, so it is not specific to infection on its own.
Why would a doctor order both ESR and CRP?
ESR and CRP change at different speeds, so ordering both can give a fuller picture, with CRP reflecting more recent change and ESR reflecting a slower-moving trend.
Can ESR be raised in a healthy person?
Yes. ESR naturally rises with age and can be affected by factors such as anaemia, pregnancy or obesity, so a mildly raised result in an otherwise well person is not automatically a cause for concern.
Is ESR the same as a full blood count?
No. ESR is a single, separate measurement of inflammation. It is often requested alongside a full blood count, which counts red cells, white cells and platelets, rather than in place of it.
How quickly will I get my ESR result?
Results are usually available within 1 day, sent to you by email as a laboratory report showing the result against its reference range.
Should I see a doctor if my ESR is raised?
If your ESR is raised, particularly alongside symptoms such as persistent fatigue, joint pain or unexplained weight loss, arrange to see a doctor to discuss what further assessment might help. You can also add a doctor review of your report to your test for £75.
References
- NHS: Blood tests
- Lab Tests Online UK: ESR (erythrocyte sedimentation rate)
- NHS: Giant cell arteritis
- NICE CKS: Giant cell arteritis
- NHS: Polymyalgia rheumatica