Sed Rate

Table of Contents

What is Sedimentation Rate?

The sedimentation rate, also known as sed rate or ESR (erythrocyte sedimentation rate) blood test measures how many red blood cells (erythrocytes) settle at the bottom of a test tube in one hour.  When inflammation is present red blood cells can stick together and fall more quickly than normal to the bottom of the tube.  This test is very non-specific, a high sed rate indicates inflammation but not the cause or location.

Why it is done?

This test is used in conjunction with other tests to diagnose Lupus and to monitor disease activity. 

How is it done?

Laboratories take a small sample of blood, usually from the arm.  The blood is placed in a special test tube.  After one hour, the number of red blood cells that have settled at the bottom are counted.

Normal Levels: (normal values may vary from lab to lab)

Men should have a sed rate of 20 or less.  Women should have a sed rate of less than 30. 

What a negative Sedimentation Rate means:

A negative sed rate generally indicates that no inflammation is present.

What a positive Sedimentation Rate means:

A positive sedimentation rate indicates that inflammation is present.  As stated previously, this test does not indicate the location or cause of the inflammation.