Erythrocyte Sedimentation Rate (ESR): Levels, Conditions, and More

Medically Reviewed By Deborah Weatherspoon, Ph.D., R.N., CRNA
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Erythrocyte sedimentation rate (ESR) is the rate at which red blood cells settle in a test tube. An ESR test is a tool that can help with the diagnosis or monitoring of certain conditions. Clinicians use this test to detect higher levels of inflammation in the body. Clinicians do not use ESR alone to diagnose an illness or condition. However, it can help your doctor evaluate your overall health and determine if you have higher levels of inflammation in the body.

An ESR test involves taking a sample of blood from a person and using it in a laboratory study.

This article provides a detailed overview of ESR, including how it works, what doctors may use it for, and what to expect from the procedure and your results.

What is an ESR blood test?

A female sits on a bed, wrapped up in a duvet, holding her hand to her forehead with her eyes closed.
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An ESR test is a type of blood test that can help detect higher levels of inflammation in the body.

Inflammation is a typical part of the body’s immune response to infection or injury. However, higher-than-necessary levels of inflammation may occur due to infections, chronic conditions, or other health conditions.

Clinicians can use one of two ESR techniques: the Westergren method or the Wintrobe method.

Both techniques measure the rate at which red blood cells fall to the bottom of an upright, elongated tube over 1 hour. However, the Westergren method is more common and more sensitive, meaning that it may give more precise results.

What does it show?

An ESR test measures the rate at which erythrocytes, or red blood cells, settle to the bottom of a test tube. This process of falling is called sedimentation.

If the red blood cells settle more quickly than expected, this may indicate inflammation in the body.

Quicker settling can happen when the red blood cells have more protein in them, causing them to stick together. This can occur as a result of many different inflammatory conditions.

What is ESR used for?

An ESR test is not a test specific to the diagnosis of any one disease or condition. Instead, clinicians can use an ESR test to assess inflammation in the body. This may help determine if you have a condition that causes inflammation. Alternatively, it can help your doctor monitor inflammatory activity.

Clinicians may use ESR to:

  • monitor an existing condition
  • determine whether or not an illness is responding to treatment
  • see how inflammatory health conditions change over time

Clinicians do not use ESR to diagnose an illness or condition. Instead, your doctor will make a diagnosis using information from an ESR test combined with the results of other tests, such as a complete blood count.

This will help your doctor evaluate your overall health and look for signs of specific health problems.

When might you need an ESR test?

Your doctor may order an ESR test if you are experiencing new or worsened symptoms of an inflammatory condition, such as:

ESR test procedure

If your doctor has ordered an ESR test, you will need to give a blood sample. This usually takes place at a doctor’s office, at the hospital, or in an urgent care facility.

There is nothing you need to do to prepare for the blood sample. Also, the procedure can be very quick, lasting just several minutes.

To take a blood sample, a clinician will insert a small needle into a vein, often on the arm. This will allow them to collect a small amount of blood into a test tube or vial to be sent to a laboratory for testing. You may feel mild to moderate pain while the clinician uses the needle.

If you are not comfortable with needles or the sight of blood, discuss your situation with your clinician to see if there is any support they can offer you.

Risks

Generally, there is very little risk involved with giving a blood sample for testing.

However, after the procedure, you may experience throbbing or bruising at the puncture site. That said, most symptoms resolve quickly.

Contact your doctor if you notice any persistent symptoms of infection or side effects, including:

  • redness or other skin discoloration
  • swelling
  • pain that does not improve or go away

ESR test results

Clinicians measure an ESR value in millimeters per hour (mm/hr).

The expected ESR value range for a healthy person varies based on age and sex assigned at birth. For example, females tend to have higher ESR values than males, and ESR values gradually increase with age.

Exact ESR values may also vary between different laboratories.

The following table outlines the results of ESR tests by age and sex assigned at birth.

Age and sex assigned at birthExpected ESR results rangeUnusual ESR results range
adult females under the age of 50 yearsless than 20 mm/hrabove 20 mm/hr
adult females over the age of 50 yearsless than 30 mm/hrabove 30 mm/hr
adult males under the age of 50 yearsless than 15 mm/hrabove 15 mm/hr
adult males over the age of 50 yearsless than 20 mm/hrabove 20 mm/hr
children of any sexless than 10 mm/hrabove 10 mm/hr

Accuracy

Certain factors can affect the results of your ESR test. For example, direct sunlight can affect the texture of the blood after its withdrawal. This can increase your ESR value.

Other factors that may affect ESR results include:

  • variations in room temperature
  • time from sample collection, as the test should take place within 2 hours of collection
  • the use of certain medications, including oral birth control pills, vitamins, and aspirin
  • pregnancy
  • menstruation
  • older age
  • exercise
  • regular alcohol intake

If any of these factors have affected your blood sample, you may have to do a repeat sample and test.

If you have any questions or concerns about the accuracy of your ESR test, discuss them with your doctor. Always disclose what medications and supplements you are taking to your clinician before testing.

High or low results do not always mean severe illness

Due to the factors that can interfere with ESR results, an unusual result may not always indicate illness. Sometimes, these factors can be benign, meaning that they do not represent a threat to health.

For example, if your results are slightly higher than the expected range, this may not indicate any condition or any condition that requires treatment.

Researchers suggest that if ESR levels are slightly different than what your doctor expects, but you have no other concerning signs of illness, you may not need further testing. Instead, doctors may choose to repeat an ESR test later to see how your levels change.

In such cases, an ESR that is continuously high or low may require more diagnostic testing or clinical care.

What does a high or elevated ESR mean?

If your red blood cells fall faster than expected to the bottom of the test tube, your ESR may be high.

A significantly or consistently elevated ESR may indicate the presence of a health condition. Alternatively, if you already have a diagnosis of an underlying condition, it may indicate a progression of your condition or a lack of response to treatment.

Conditions that can cause a high ESR result include:

What does a low ESR mean?

It is possible to have an ESR result that is low or lower than expected.

This can be the result of conditions such as:

What to expect after your ESR test

If you do receive a high or low result from an ESR test that your doctor suspects may relate to an underlying condition, they may order more diagnostic testing or continue to investigate your condition.

This may involve referring you to a specialist to help determine the exact cause of your condition and the best path for treatment.

If your doctor finds that an underlying condition is causing an unusual test result, you may require treatment. This treatment will vary depending on the exact condition causing inflammation and its severity. For example, if you have a serious bacterial infection, your doctor may prescribe antibiotics.

Certain medications, such as nonsteroidal anti-inflammatory drugs and corticosteroids, can also treat inflammation if necessary.

Summary

An ESR test is a blood test that measures the amount of inflammation in your body. Your doctor can use this information to assess your overall health, monitor an existing condition, or gauge the effectiveness of treatment. It works by measuring how quickly red blood cells fall to the bottom of a test tube.

If you have certain symptoms of illness or inflammation, your doctor may recommend an ESR test, along with other tests, to help diagnose an underlying illness or condition.

A typical ESR value is based on age and sex assigned at birth, with higher or lower rates being a possible indication of illness.

Certain benign conditions, medications, and activities can also cause your ESR to be slightly higher or lower. Discuss what medications you are taking and what you may expect from the procedure with your doctor.

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Medical Reviewer: Deborah Weatherspoon, Ph.D., R.N., CRNA
Last Review Date: 2022 Jun 28
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