What this marker measures
ESR is one of the oldest blood tests still in routine use. It rises and falls more slowly than CRP — ESR can remain elevated for weeks even after the cause has resolved. It is used to monitor conditions like rheumatoid arthritis, temporal arteritis, and polymyalgia rheumatica.
High or low: what it can mean
High ESR
An elevated ESR indicates the presence of inflammation, infection, or tissue damage. It is a non-specific marker — a high result requires further investigation to find the underlying cause.
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Low ESR
A low ESR is generally not clinically significant. Sickle cell disease, polycythemia, and certain medications can cause a falsely low ESR.
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Lifestyle considerations
- •ESR naturally increases slightly with age; separate reference ranges exist for older adults
Frequently asked questions
What is ESR?
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ESR measures how quickly red blood cells sink to the bottom of a blood sample over one hour. Inflammation causes proteins in blood to make cells clump and fall faster.
What does ESR measure?
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ESR is one of the oldest blood tests still in routine use. It rises and falls more slowly than CRP — ESR can remain elevated for weeks even after the cause has resolved. It is used to monitor conditions like rheumatoid arthritis, temporal arteritis, and polymyalgia rheumatica.
What does high ESR mean?
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An elevated ESR indicates the presence of inflammation, infection, or tissue damage. It is a non-specific marker — a high result requires further investigation to find the underlying cause.
What does low ESR mean?
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A low ESR is generally not clinically significant. Sickle cell disease, polycythemia, and certain medications can cause a falsely low ESR.
What supports healthy ESR levels?
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ESR naturally increases slightly with age; separate reference ranges exist for older adults
Related biomarkers
Editorial note
LabTestly explains lab markers using plain-English educational content. Reference ranges may vary by laboratory and should be interpreted with a clinician.
Educational content · Editorially reviewed for clarity · Last updated
Common sources used for lab-test education
Not medical advice
This page is for general understanding only and does not replace medical advice from your clinician. Reference ranges can vary by laboratory, age, sex, pregnancy status, medications, and clinical context.