Test Quick Guide

The erythrocyte sedimentation rate, also known as ESR, is based on how quickly red blood cells (RBCs) settle inside a test tube.

An ESR test is used to assess inflammation in the body. Many conditions can cause an abnormal ESR, so an ESR test is typically used with other tests to diagnose and monitor different diseases.

About the Test

Purpose of the test

The main purpose of an ESR test is to detect abnormal levels of inflammation in the body. Measuring ESR is primarily used for diagnosis and monitoring of different health conditions:

  • Diagnosis is the process of finding the cause of a patient’s symptoms. Because many health problems can cause an ESR test to be abnormal, the test alone cannot diagnose conditions. However, when combined with other tests, an ESR test may help detect infections, autoimmune diseases, blood disorders, kidney disease, and many other health problems.
  • Monitoring is the process of periodically assessing a patient’s health after a diagnosis. An ESR test may be used periodically to see how inflammatory health conditions change over time. It can also help assess a patient’s response to treatments for certain disorders.

It is important to talk with your health care provider for more details about the specific purpose of ESR testing in your situation.

What does the test measure?

An ESR test measures how fast RBCs, also known as erythrocytes, fall to the bottom of a test tube. The falling of these cells is called sedimentation, which is measured in millimeters per hour (mm/h).

When should I get an erythrocyte sedimentation test?

An ESR test may be appropriate if you have unexplained symptoms like a fever, muscle or joint pain, or other problems without a clear cause. In these situations, an ESR is usually combined with other tests, such as a complete blood count, comprehensive metabolic panel, and arthritis tests, to evaluate your overall health and look for signs of specific health problems.

Your doctor may also recommend an ESR test to help track your health if you have previously been diagnosed or received treatment for infections, autoimmune diseases, or other inflammatory health conditions.

Finding an Erythrocyte Sedimentation Rate Test

How can I get a test?

An ESR test requires a blood sample and is typically conducted at a doctor’s office, urgent care facility, or hospital. The test usually has to be ordered by a health care provider. The person conducting the test will either be a phlebotomist who is trained to draw blood or another health care professional.

You can also order an ESR test online with the blood draw and testing performed by a Clinical Laboratory Improvement Amendments (CLIA) approved lab.

Can I take the test at home?

An ESR test typically cannot be conducted at home. It has to be done by a trained medical professional in a medical setting where the blood can be quickly analyzed after it has been drawn. It is possible to use a mobile phlebotomy service, but there are no self-collection tests available

How much does the test cost?

The price of an ESR test varies based on where you have the test done and whether you have health insurance. The cost of the test may increase if you have other tests performed along with an ESR.

If you want to know more about the cost of the procedure and how much your insurance covers, contact your insurance company. If you do not have any kind of health insurance coverage, you can ask the testing facility about any available financial assistance programs for the uninsured.

Taking an Erythrocyte Sedimentation Test

The ESR test is performed with a sample of blood that is drawn from a vein in your arm. The blood draw process is typically carried out in a medical office, lab testing site, or hospital.

Before the test

There is no special test preparation required for an ESR test. Before the test, make sure to tell your doctor about any drugs or supplements that you take because some medications may affect your results.

During the test

The blood draw for an ESR test usually only takes a few minutes to perform.

The health professional taking your blood sample will start by using an alcohol wipe to clean a small area of your skin near a vein. A needle will then be inserted into the vein, and blood will be drawn into an attached tube. Once enough blood has been drawn, the needle is removed.

There may be some pain, such as a pinch or sting, when the needle pierces the skin and is removed from your arm.

After the test

Most people do not have any negative reactions to an ESR test, but you may have some bruising or tenderness around the puncture site. There are no activity restrictions after the test, but contact your doctor if you notice any signs of infection such as redness, swelling, or persistent pain.

Erythrocyte Sedimentation Rate Test Results

Receiving test results

An ESR test is usually performed within a couple of hours after your blood is drawn, and the RBCs in the test tube are monitored for one hour to determine the ESR.

Once the results are available, you may receive a test report by mail or electronically. Your doctor may also contact you to discuss your ESR test results.

If multiple tests are being performed along with the ESR test, your doctor may wait for all the results to be available before discussing the results with you. This allows them to interpret the test results together.

Interpreting test results

The ESR is reported in millimeters per hour (mm/h) and reflects how quickly the RBCs in your sample fall toward the bottom of a test tube.

There is no universal definition of a normal ESR. Age, sex, and other factors can influence ESR, so there is no reference range for this test that applies to all people.

Instead, the results of testing are interpreted based on an individual’s situation. This includes considering their symptoms and the results of any other tests that have been performed.

If an ESR is abnormally high, it means that the RBCs fell faster than expected. This usually happens when the RBCs have more protein within them, which causes them to stick together.

Many conditions can cause an ESR to become elevated. Most often, an elevated ESR is related to conditions that cause inflammation, but it can also be caused by other health problems. Examples of conditions that can cause an abnormally high ESR include:

  • Infections
  • Autoimmune conditions like lupus and rheumatoid arthritis
  • Anemia
  • Kidney or thyroid disease
  • Some types of cancer
  • Tissue injury or trauma

It is also possible for the ESR to be lower than expected. This may be caused by conditions such as:

  • RBC disorders
  • Heart failure
  • Some liver and kidney problems

It is important to remember that an ESR test alone cannot diagnose any disease or medical condition. It must be used in conjunction with other tests to detect and monitor health problems. An ESR test should always be interpreted by a doctor who can explain its significance.

When going over your test results with the doctor, the following questions can be helpful:

  • Did the test detect any abnormalities?
  • If so, what kind of abnormal result was detected?
  • What is the most likely explanation for my test result?
  • What other tests were conducted along with the ESR?
  • Do I need any follow-up testing?



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