An erythrocyte sedimentation rate (ESR), also known as a sed rate, is a blood test that measures how quickly red blood cells settle to the bottom of a test tube. This rate of settling is influenced by the level of certain proteins in your blood, which can indicate the presence of inflammation in your body. Inflammation is your body's natural response to injury, infection, and many types of conditions, including immune system disorders, certain cancers, and blood disorders.
The ESR test is a relatively simple and inexpensive test that can be helpful in diagnosing a variety of conditions. However, it is not a definitive test for any specific condition, and it is often used in conjunction with other tests and clinical assessments.
How is ESR Performed?
The ESR test is performed by drawing a small sample of blood from a vein in your arm. The blood is then placed in a special test tube and allowed to settle. The time it takes for the red blood cells to settle to the bottom of the tube is measured in millimeters per hour (mm/hr).
What does a high ESR mean?
A high ESR can indicate the presence of inflammation in your body. It can be caused by various factors, including:
- Infections: Bacterial, viral, or fungal infections can trigger inflammation.
- Autoimmune diseases: Conditions like rheumatoid arthritis and lupus can cause chronic inflammation.
- Cancers: Some cancers can release proteins that cause inflammation.
- Tissue injury: Trauma, surgery, or other injuries can trigger inflammation.
- Other conditions: Conditions like anemia, kidney disease, and pregnancy can also affect ESR levels.
What does a low ESR mean?
A low ESR usually indicates that there is no inflammation in the body. However, a low ESR may not always be a sign of good health.
Limitations of the ESR test:
- Not specific: A high ESR doesn't always indicate a specific condition.
- Not always accurate: Some people may have a high ESR without any inflammation, while others may have low ESR even with inflammation.
- Not diagnostic: It's not a definitive test for any specific condition.
Factors influencing ESR:
- Age: ESR tends to be slightly higher in older adults.
- Gender: ESR is typically slightly higher in women than in men.
- Pregnancy: ESR is typically higher during pregnancy.
- Medications: Some medications, such as corticosteroids, can affect ESR levels.
The ESR test is often used to monitor the progress of treatment for inflammatory conditions.
