Sedimentation Rate
(Erythrocyte Sedimentation Rate or ESR)

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Medical Author: William C. Shiel Jr., MD, FACP, FACR

• What is a sedimentation rate?
• How is a sedimentation rate performed?
• What is the normal sedimentation rate?

What is a sedimentation rate?

A sedimentation rate is common blood test that is used to detect and monitor inflammation in the body. The sedimentation rate is also called the erythrocyte sedimentation rate because it is a measure of the red blood cells (erythrocytes) sedimenting in a tube over a given period of time. Sedimentation rate is often abbreviated as sed rate or ESR.

How is a sedimentation rate performed?

A sedimentation rate is performed by measuring the rate at which red blood cells (RBCs) settle in a test tube. The RBCs become sediment in the bottom of the test tube over time, leaving the blood serum visible above. The classic sedimentation rate is simply how far the top of the RBC layer has fallen (in millimeters) in one hour. The sedimentation rate increases with more inflammation.

What is the normal sedimentation rate?

The normal sedimentation rate (Westergren method) for males is 0-15 millimeters per hour, females is 0-20 millimeters per hour. The sedimentation rate can be slightly more elevated in the elderly.