ESR

Also known as: Erythrocyte sedimentation rate

Related tests: C-reactive protein (CRP); fibrinogen; immunoglobulins

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.

If you don't know what a word or a medical term means, try the Mondofacto Online Medical Dictionary .