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ESR Blood Test: What Your Results Mean

ESR (erythrocyte sedimentation rate) measures how quickly red blood cells settle to the bottom of a test tube in one hour. When inflammation is present, the blood contains more proteins (such as fibrinogen) that cause red blood cells to clump together and settle faster. ESR is a non-specific marker — a high result tells you inflammation or disease is present, but not where or why. It is usually interpreted alongside CRP, a full blood count, and clinical symptoms.

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Normal Range

0 – 20 mm/hr (men), 0 – 30 mm/hr (women)

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Unit

mm/hr

What Your Results Mean

Normal

A normal ESR indicates a low level of systemic inflammation. Red blood cells are not clumping together abnormally, suggesting no significant active infection, autoimmune flare, or inflammatory process.

High

A high ESR indicates inflammation somewhere in the body. It is elevated in infections (bacterial, viral, fungal), autoimmune diseases (rheumatoid arthritis, lupus, vasculitis), inflammatory bowel disease, temporal arteritis (giant cell arteritis), cancer, kidney disease, anaemia, and pregnancy. Extremely high ESR (above 100 mm/hr) is associated with serious conditions including multiple myeloma, metastatic cancer, severe infection, and temporal arteritis.

Low

A very low ESR is generally not clinically significant. It may occasionally be seen in polycythaemia (too many red blood cells) or sickle cell disease, where the abnormal shape of red blood cells prevents them from clumping.

Frequently Asked Questions

What does a high ESR mean? expand_more
A high ESR indicates that inflammation is present in the body. Common causes include bacterial or viral infections, autoimmune diseases (rheumatoid arthritis, lupus), inflammatory bowel disease, anaemia, kidney disease, and cancer. The ESR alone cannot identify the cause — further testing is always required.
What is the difference between ESR and CRP? expand_more
Both are markers of inflammation, but they differ in speed of response. CRP rises and falls within hours, making it ideal for monitoring acute inflammation and infection. ESR changes more slowly — rising over days and normalising over weeks — making it better for tracking chronic inflammatory conditions. They complement each other.
What is the normal ESR range? expand_more
Normal ESR is 0 to 20 mm/hr in men and 0 to 30 mm/hr in women, though the upper limit of normal increases with age. Women naturally have slightly higher ESR due to oestrogen effects on blood proteins. ESR also rises normally during pregnancy.
Can a high ESR be a sign of cancer? expand_more
Yes, ESR can be elevated in cancer, particularly haematological cancers such as multiple myeloma and lymphoma, and in solid tumours with extensive metastases. An unexplained very high ESR (over 100 mm/hr) should always prompt a thorough investigation to exclude serious underlying conditions.
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