ESR

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Also known as: Erythrocyte sedimentation rate

At a Glance

Why Get Tested?

To detect and monitor the activity of inflammation as an aid in the diagnosis of the underlying cause

When to Get Tested?

When your doctor thinks that you might have a condition that causes inflammation and to help diagnose and follow the course of this, especially temporal arteritis or polymyalgia rheumatica

Sample Required?

A blood sample taken from a vein in the arm

The Test Sample

What is being tested?

ESR is an indirect measure of the degree of inflammation present in the body. It actually measures the rate of fall (sedimentation) of erythrocytes (red blood cells) in a tall, thin tube of blood. Results are reported as how many millimetres of clear plasma are present at the top of the column after one hour. Normally, red cells fall slowly, leaving little clear plasma. Increased blood levels of certain proteins (such as fibrinogen or immunoglobulins, which are increased in inflammation) cause the red blood cells to fall more rapidly, increasing the ESR.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in your arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

The Test

Common Questions

Ask a Laboratory Scientist

Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.