What is an Erythrocyte Sedimentation Rate (ESR)?
An erythrocyte sedimentation rate (ESR) is a type of blood test that measures how quickly erythrocytes (red blood cells) settle at the bottom of a test tube that contains a blood sample. Normally, red blood cells settle relatively slowly. A faster-than-normal rate may indicate inflammation in the body. Inflammation is part of your immune response system. It can be a reaction to an infection or injury. Inflammation may also be a sign of a chronic disease, an immune disorder, or other medical condition.
Other names: ESR, SED rate sedimentation rate; Westergren sedimentation rate
What is it used for?
An ESR test can help determine if you have a condition that causes inflammation. These include arthritis, vasculitis, or inflammatory bowel disease. An ESR may also be used to monitor an existing condition.
Why do I need an ESR?
Your health care provider may order an ESR if you have symptoms of an inflammatory disorder. These include:
What happens during an ESR?
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for an ESR?
You don't need any special preparations for this test.
Are there any risks to the test?
There is very little risk to having an ESR. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
If your ESR is high, it may be related to an inflammatory condition, such as:
- Rheumatoid arthritis
- Rheumatic fever
- Vascular disease
- Inflammatory bowel disease
- Heart disease
- Kidney disease
- Certain cancers
Sometimes the ESR can be slower than normal. A slow ESR may indicate a blood disorder, such as:
- Sickle cell anemia
- Leukocytosis, an abnormal increase in white blood cells
If your results are not in the normal range, it doesn't necessarily mean you have a medical condition that requires treatment. A moderate ESR may indicate pregnancy, menstruation, or anemia, rather than an inflammatory disease. Certain medicines and supplements can also affect your results. These include oral contraceptives, aspirin, cortisone, and vitamin A. Be sure to tell your health care provider about any drugs or supplements you are taking.
Is there anything else I need to know about an ESR?
An ESR does not specifically diagnose any diseases, but it can provide information about whether or not there is inflammation in your body. If your ESR results are abnormal, your health care provider will need more information and will likely order more lab tests before making a diagnosis.
- Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Erythrocyte Sedimentation Rate (ESR); p. 267–68.
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