Erythrocyte sedimentation rate (ESR)
Non-specific inflammation marker: how fast red blood cells settle in a test tube
Also known as
Definition
The erythrocyte sedimentation rate (ESR) measures how quickly red blood cells sink to the bottom of a tall, thin tube, given in millimeters per hour. With inflammation, red blood cells clump together more easily and sink faster. The test thus indirectly reflects certain proteins in the blood. The ESR shows that inflammation may be present, but not what is causing it. It is therefore usually measured together with CRP and other values.
| Parameter | Value |
|---|---|
| Unit | mm/h (Westergren method) |
| Reference Range | Typical upper limits for adults (Westergren): men under 50 below 15 mm/h, over 50 below 20 mm/h; women under 50 below 20 mm/h, over 50 below 30 mm/h. Labs differ; the range on your own report is what counts. Discuss it with your doctor. |
Agree on your personal target range with your doctor.
↓ What a low value means
If red blood cells settle more slowly than usual, this can be linked to blood disorders such as polycythemia (too many red blood cells), sickle cell disease or a very high white cell count, and also to heart failure, low fibrinogen or low plasma protein due to liver or kidney disease. A normal ESR does not rule out inflammation. Discuss any deviation with your doctor.
↑ What a high value means
A raised ESR means the red blood cells settled faster than usual. This can be linked to infections, rheumatoid arthritis and other autoimmune diseases, polymyalgia rheumatica, inflammation of blood vessels such as giant cell arteritis, inflammatory bowel disease, kidney disease, anemia, thyroid disease or certain cancers. Age, pregnancy, menstruation, obesity, regular alcohol use, exercise and some medicines and supplements also affect the value. The ESR alone cannot make a diagnosis; discuss any deviation with your doctor.
When to test
The ESR is ordered when an inflammatory condition is suspected, for example with unexplained fever, unintended weight loss, headaches, joint stiffness or neck and shoulder pain, and to monitor known conditions. No special preparation is needed; fasting may be required if other values are measured from the same sample. Tell the practice about any medicines and supplements you take.
Frequently asked questions
What is the difference between ESR and CRP? +
Both indicate inflammation non-specifically, without naming its cause. The ESR measures indirectly via how fast red blood cells settle, while C-reactive protein (CRP) is a single protein measured directly. They are often ordered together because they complement each other.
Can the ESR be normal despite inflammation? +
Yes. An inflammatory condition can occur with a normal ESR. That is why your doctor always interprets the value together with your symptoms, history and other lab values.
Why are there different limits for women and men? +
Usual ESR values depend on age and sex. Labs therefore give separate upper limits; they are higher for women and for people over 50. Pregnancy and menstruation also change the value.
Do I need to fast for an ESR? +
No preparation is needed for the ESR itself. If other values are measured from the same blood sample, you may be asked to fast for several hours. Your practice will tell you what applies.
Erythrocyte sedimentation rate (ESR)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.