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Erythrocyte Sedimentation Rate (ESR)

A simple blood test that shows how fast red blood cells settle in a tube. A faster rate can be a sign of inflammation somewhere in the body.

AI-verified against cited sources. Awaiting expert reviewAlso called ESR, BSG, VSGLOINC 4537-7

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What it is

ESR measures how far your red blood cells sink in a narrow tube of blood over one hour, reported in millimeters per hour (mm/hr). When inflammation is present, proteins in the blood make red cells stick together in stacks, and the stacks sink faster. The test does not say where the inflammation is or what is causing it. Most labs use the Westergren method or an automated version calibrated to match it.

Why it matters

ESR is a broad, low-cost signal that something may be inflaming the body. Clinicians use it when symptoms such as joint pain, fever, headache or unexplained weight loss need explaining, and to follow some long-term inflammatory conditions over time. It is often paired with a C-reactive protein (CRP) test. ESR is not specific and it is easily nudged by age, sex, pregnancy and anemia, so a high or normal value never settles a question on its own.

If it’s low

A low ESR is common and usually not a cause for concern on its own. Some people simply sit toward the low end of the range. A lower rate can also reflect how crowded the blood is with cells or proteins rather than a lack of inflammation.

Common causes

  • Normal variation between people
  • A high red blood cell count (polycythemia)
  • A very high white blood cell count (leukocytosis)
  • Sickle cell disease
  • Heart failure
  • Some kidney or liver problems

What can help

  • Nothing is usually needed for a low result alone
  • If you have symptoms, ask whether your blood count or other tests explain it

If it’s high

A higher ESR means your red blood cells settled faster than the usual range for your age and sex. It is a sign that inflammation may be present, but it is a general signal and can have many causes. Mildly high values are common and are often explained by ordinary factors. Your clinician reads it together with your symptoms, exam and other tests.

Common causes

  • Older age and female sex, which raise the usual range
  • Pregnancy
  • Anemia
  • Obesity
  • Infections
  • Inflammatory arthritis, such as rheumatoid arthritis, and other autoimmune conditions
  • Polymyalgia rheumatica, giant cell arteritis and other forms of vasculitis
  • Inflammatory bowel disease
  • Kidney disease
  • Some cancers and blood disorders, such as multiple myeloma (these are more often behind very high results, above 100 mm/hr)

What can help

  • Ask your clinician whether a CRP test and a complete blood count would help put the number in context
  • Share your medicines and supplements, since some can affect the result
  • If you were recently ill or pregnant, ask whether it makes sense to recheck once things settle

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex and age. Choose women or men to see the one that applies.

See ESR by age and sex, with the U.S. survey numbers where they exist.

What can affect your result

  • Age and sex: the usual range is higher in women and rises with age
  • Pregnancy, which raises ESR significantly, mainly in the 2nd and 3rd trimesters
  • Anemia (raises ESR) and high red-cell counts or sickle cells (lower it)
  • Obesity, regular alcohol use, the menstrual cycle and exercise
  • Certain medicines and supplements
  • Sample handling and the method your lab uses
  • Anemia can raise ESR and a very high red-cell count or sickle cells can lower it, whatever the level of inflammation.
  • Pregnancy, older age, female sex, obesity, regular alcohol use and recent exercise can all shift ESR.
  • Certain medicines and supplements can change the result. Tell your clinician what you take.
  • A sample that waits too long before testing can give a different result, so labs set time limits for ESR samples (Testing.com notes about 2 hours).

Changes slowly. ESR can take days to rise and can stay high for weeks after the cause of inflammation has settled.

When to talk to a clinician

Talk with a clinician soon if your ESR is above 100 mm/hr, or if a raised ESR comes with a new, persistent headache or scalp tenderness, jaw pain when chewing, new shoulder or hip stiffness, fever with weight loss, or joint swelling. Sudden changes in vision need urgent care whatever your ESR is.

Questions you could ask

  • What are you using ESR to look for, or to follow?
  • If I'm being monitored, how often should it be repeated?
  • Could my age, anemia, pregnancy or a recent illness explain this result?
  • Should we check CRP or a blood count alongside it?
  • Should we repeat it in a few weeks to see whether it changes?
  • Could my blood count explain a low ESR?

Questions people ask

Can my ESR be normal if I have inflammation?

Yes. A normal ESR does not rule out inflammation, especially early on or when it is limited to one area. A high ESR also does not confirm any one condition. That is why clinicians combine it with your symptoms, an exam and other tests.

What is the difference between ESR and CRP?

Both are general signs of inflammation. CRP rises and falls within hours to days, so it is better for tracking sudden changes. ESR responds more slowly and can stay high for weeks after the cause has settled. They are often ordered together.

Does a high ESR mean something serious?

Not by itself. Mildly high values are common and can come from age, pregnancy, anemia or a recent infection. A very high result (above 100 mm/hr) is less common and is worth a prompt conversation with your clinician.

Show the science and sources

For clinicians and researchers

ESR reflects the rate of red cell aggregation (rouleaux formation) and sedimentation in anticoagulated blood. Acute-phase proteins, mainly fibrinogen, and immunoglobulins promote aggregation, while a higher hematocrit slows sedimentation and anemia speeds it. ESR rises over days and falls over weeks, so it lags CRP, which moves within hours. The ICSH (2011) reference method is Westergren, using EDTA blood diluted 4:1 with sodium citrate or saline, or blood collected in citrate 4:1, in Westergren pipettes with a 200 mm scale and 2.55 mm bore. Automated and modified methods are validated against it over a range of about 2 to 120 mm, so values from different instruments are close but not identical. Upper reference limits rise with age and are higher in women, and age-adjusted limits have been proposed (for example, Miller et al., BMJ 1983); standard adult ranges do not apply in pregnancy. The ranges used here are the commonly cited Westergren limits (<15, <20 and <30 mm/hr). A 2025 Westergren study in an Italian hospital population found upper limits of 14 mm/hr for men aged 18 to 69 and 22 mm/hr for women aged 18 and older, so published limits differ by source and lab, and lab-printed limits take priority. ESR is unreliable in severe anemia, sickle cell disease and spherocytosis, and a normal ESR does not exclude inflammatory disease, particularly in its early stages.

LOINC 4537-7 (primary), 30341-2, 82477-1. Specimen: whole-blood.

Sources

  1. Sedimentation Rate (ESR): What It Measures & Test Results, Cleveland Clinic (2026)
  2. ESR Blood Test: Order, Results & What They Mean, Testing.com (OneCare Media), citing StatPearls
  3. Erythrocyte Sedimentation Rate (ESR), MedlinePlus, National Library of Medicine (2024)
  4. ICSH review of the measurement of the erythrocyte sedimentation rate, International Journal of Laboratory Hematology (International Council for Standardization in Haematology) (2011)
  5. Erythrocyte Sedimentation Rate Reference Intervals Determined via VES-MATIC 5 and CUBE 30 Touch with Respect to the Westergren Method, Diagnostics (MDPI) (2025)
  6. Simple rule for calculating normal erythrocyte sedimentation rate, British Medical Journal (Clinical Research Ed.) (1983)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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