Sed Rate Inflammation and Autoimmunity

[Guest guest]

Dear Group,

Since we don't have a doctor member in our group yet who wishes to be

our " medical advisor " I am borrowing a post made by Dr. Hoy, who

posted this to Jim's Vasculitis Group:

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What is the Sed Rate?

The Erythrocyte Sedimentation Rate (ESR or Sed Rate) is a very simple

test that the lab can run on a fresh blood sample. The test is run by

putting a few milliliters of whole, anticoagulated blood into a long

slender tube. The tube is then placed in a rack and allowed to stand

for 60 minutes. After the 60 minute incubation, the distance that the

erythrocytes (red blood cells, or RBC) have settled is measured.

Everyoneís blood will show some settling during the 60 minute period.

What is a normal Sed Rate?

The normal values for the Sed Rate are usually accepted to be 0-15 mm/hr

for males, and 0-20 mm/hr for females. However, age can also cause a

slight increase in ESR, so some labs use these formulas: [(age divided

by 2)=normal ESR] for males and [(age+10) divided by 2=normal ESR] for

females.

What causes an elevated Sed Rate?

The rate at which the blood cells settle is actually a very intricate

set of interactions between the cells and the proteins in the blood

plasma. The proteins in the plasma increase the viscosity of the

plasma, so the more proteins, the slower the Sed Rate. During

inflammatory reactions, many plasma proteins move out of the blood

stream to the tissues that are inflamed. The lower levels of plasma

proteins lead to an increased Sed Rate. Anemia can also cause the Sed

Rate to increase, because if there are fewer red blood cells in the

whole blood, they will settle faster. Some labs use a correction factor

to correct the Sed Rate for severely anemic patients

What does an elevated Sed Rate mean?

Elevation of the Sed Rate usually indicates that an inflammatory process

is happening somewhere in the body. The Sed Rate does not indicate any

specific disease process, nor does it indicate the prognosis for the

patient. Multiple Sed Rates measured during and after the inflammatory

process may be helpful in predicting remission from the inflammation.

The ESR is elevated in a lot of different conditions.

What other test might be abnormal when the Sed Rate is elevated?

Often the C-Reactive Protein (CRP) is also elevated.

Some labs are looking at a test that measures plasma viscosity

directly. The advantage of the viscosity test is that it is not subject

to interference from anemia or age.

And here is the promised information on the CRP Test:

What is CRP?

CRP is an abbreviation for " C-Reactive Protein " . This protein was first

discovered in the blood of patients who had streptococcal infections.

It reacted with a portion of the streptococci that is called " C

Carbohydrate " , hence it was designated " C-Reactive Protein. " Even

though it was fist found in Strep infections, we now know that it can

be seen in virtually all infectious diseases, and in many inflammatory

processes. It is one of a group of proteins called " acute phase

reactants " that can be found in the blood during inflammatory or

infectious processes.

What is a normal CRP level?

For inflammatory processes, Normal CRP is usually considered to be less

than 1.0 mg/dl. Moderate inflammation is characterized by levels

between 1.0 and 10.0 mg/dl, and values above 10.0 mg/dl are considered

a sign of marked inflammation.

What causes an elevated CRP?

When inflammation occurs, the body has a number of non-specific

responses to help combat what it perceives to be a potential infection.

Several proteins are produced that have activity against microbes, CRP

being one of these.

What does an elevated CRP mean?

Elevation of the CRP usually indicates that an inflammatory process is

happening somewhere in the body. The CRP does not indicate any

specific disease process, nor does it indicate the prognosis for the

patient.

Multiple CRP levels measured during and after the inflammatory process

may be helpful in predicting remission from the inflammation. The CRP

is elevated in a lot of different conditions.

What about CRP and Coronary Artery Disease?

In the past few years, very sensitive CRP assays have been used to

detect levels of CRP that are in the " normal " range (0-1.0 mg/dl).

Some of these studies have shown that low levels of CRP are seen in

patients who have atherosclerotic plaque in their coronary arteries.

At least one of these studies showed a strong correlation between this

persistent CRP and heart attacks in women.

How do the CRP and Sed Rate Compare?

They are both tests that measure inflammation, but they are affected

by different aspects of the inflammatory process. The CRP appears

very rapidly (within a few minutes) when an inflammatory process

begins, and tends to drop after several days. The Sed Rate tends to

come up more slowly (a few days after onset of the inflammation), and

persists for a longer period of time. In chronic inflammation, like

we see in autoimmune diseases, both CRP and Sed Rate may stay elevated

for long periods of time. Depending on the source of the

inflammation, the CRP and Sed Rate may give very different results

* S. Hoy, Ph.D., SI(ASCP)

* Clinical Associate Professor

* Department of Medical Laboratory Sciences

* The University of Texas Southwestern Medical Center at Dallas