What is the Erythrocyte Sedimentation Rate (ESR)?
The Erythrocyte Sedimentation Rate (ESR) measures the rate at which red blood cells (erythrocytes) settle in a test tube in one hour. Results are reported as the millimeters of clear fluid (plasma) that are present at the top portion of the tube after one hour. This is a marker for inflammation in the body.
When inflammation is present, due to conditions such as infection, trauma, autoimmune disease or cancer, our immune system signals our liver to produce so-called “acute phase proteins”. These proteins are released into the blood cause red blood cells to adhere to each other and thereby settle faster than normal.
Why is this analysis important?
The ESR test is usually performed when inflammation or infection is suspected. ESR is an old and inexpensive test that has historically been synonymous with “inflammation test”. Although many newer and more specific markers for inflammation have appeared, ESR is still widely used in the clinic and plays an irreplaceable role in the detection and monitoring of many autoimmune diseases.
In short, it is useful to perform the ESR test to:
Identify cases of infection or inflammation
Monitor the progress of certain diseases
Monitor treatment response of certain diseases
Results
The reference range for ESR can be different depending on the laboratory and technique used. Doctors usually also take into account a number of factors when evaluating ESR values.
High ESR values may be associated with:
Autoimmune diseases, such as systemic lupus erythematosus or rheumatoid arthritis.
Chronic liver diseases
Infections like pneumonia or appendicitis
Inflammation of blood vessels or joints
Pregnancy and preeclampsia
Other types of infections and inflammations
Low ESR values may be associated with:
High blood sugar levels
Abnormal red blood cells
Liver failure
Other considerations
Increased ESR only indicates the presence of inflammation but cannot pinpoint the exact cause. To identify the cause of inflammation, further investigation by a doctor is required.
Normal ESR cannot completely rule out inflammation. ESR values should be evaluated together with other markers of inflammation such as CRP, white blood cells and ferritin.
References
Acute phase reactants. Irving Kushner, MD. UpToDate Mar 01, 2019.