Lab test, explained · Reviewed by the Medical Records Vault clinical team · Last reviewed June 2026
What is ESR (erythrocyte sedimentation rate)? Explained
ESR measures how quickly red blood cells settle in a tube over an hour. A faster rate can indicate inflammation in the body, but like CRP it does not say where or why. It is a non-specific test, interpreted alongside symptoms and other results.
- Measures
- How fast red cells settle — a marker of inflammation
- Raised may indicate
- Inflammation, but not its source
- Type
- Non-specific; read with other tests
What ESR measures
ESR stands for erythrocyte sedimentation rate. In the lab, blood is left in a thin tube and the technician measures how far the red cells settle in one hour. When there is inflammation in the body, certain proteins make red cells clump and settle faster — so a higher ESR can indicate inflammation.
A non-specific signal
Like CRP, ESR tells you inflammation may be present but not where or why. It can also be nudged by age, anemia, and pregnancy. Because it is non-specific and changes slowly, doctors read it with your symptoms and other tests, and sometimes track it over time.
Questions to ask your doctor
Bring these to your next visit. They are written to help you understand what was already decided — not to second-guess your doctor.
- 1.What might be raising my ESR?
- 2.Do I need further tests to find the cause?
- 3.Should it be repeated to track change?
Common questions
- What does a high ESR mean?
- A high ESR suggests inflammation somewhere in the body, but it is non-specific — it does not identify the cause or location. Doctors read it with your symptoms, CRP, and other tests rather than alone.
This is an educational explanation, not a diagnosis or medical advice. Medical Records Vault explains what documents say and what is commonly done; it never tells you what you have or what to change. Always consult your doctor for any medical decision.
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