Erythrocyte Sedimentation Rate (ESR)

The Erythrocyte Sedimentation Rate (ESR) is a blood test that measures how quickly erythrocytes (red blood cells) settle at the bottom of a test tube containing a blood sample. It indirectly measures how much inflammation is in the body.

Procedure

The procedure for an ESR test involves the following steps:

• A blood sample is drawn from a vein, usually from the arm.
• The blood sample is placed in a test tube containing an anticoagulant to prevent clotting.
• The test tube is left to stand upright for a specified period, usually one hour.
• The distance the red blood cells have fallen (settled) from the top of the blood column is measured and recorded in millimeters per hour (mm/h).

Principle

The principle behind the ESR test is based on the fact that inflammatory states lead to the production of acute-phase proteins, which cause red blood cells to aggregate and settle more quickly. The higher the level of inflammation, the faster the red blood cells will settle.

Reference Values

Normal reference values for ESR vary depending on age and sex:

• For men, a normal ESR is typically considered to be 0-15 mm/h.
• For women, a normal ESR is typically considered to be 0-20 mm/h.

Clinical Significance

The ESR test has several clinical applications:

• Inflammatory conditions: Elevated ESR levels can indicate the presence of inflammatory conditions such as rheumatoid arthritis, lupus, or other autoimmune diseases.
• Infections: High ESR levels can also be seen in bacterial and viral infections.
• Cancer: Some types of cancer, such as lymphoma or multiple myeloma, can cause elevated ESR levels.

Limitations

The ESR test has some limitations:

• It is a non-specific test, meaning that an elevated ESR level does not necessarily indicate a specific disease or condition.
• ESR levels can be influenced by various factors, such as age, sex, and the presence of other medical conditions.

Interpretation

Interpretation of ESR results should always be done in conjunction with clinical evaluation, medical history, and other diagnostic tests. A healthcare professional will consider the patient's overall condition and other test results to determine the significance of an elevated or normal ESR level.

Frequently Asked Questions (FAQs)

What is an ESR test?
Measures how quickly erythrocytes settle in a test tube.

Why is an ESR test done?
To detect inflammation in the body.

What does a high ESR indicate?
Inflammation or infection.

What does a low ESR indicate?
Little or no inflammation.

How is an ESR test performed?
Blood sample is taken and placed in a test tube.

Is an ESR test painful?
No, it's a standard blood draw.

How long does it usually take to get ESR results?
Usually 1-2 hours.

What can affect ESR results?
Age, sex, pregnancy, and certain medications.

Is an ESR test diagnostic?
No, it's used to monitor or support diagnosis.

What are normal ESR ranges?
Vary by age and lab, but typically 0-20 mm/h.