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
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.
Your health care provider may order an ESR if you have symptoms of an inflammatory disorder. These include:
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.
You don’t need any special preparations for this 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.
If your ESR is high, it may be related to an inflammatory condition, such as:
Sometimes the ESR can be slower than normal. A slow ESR may indicate a blood disorder, such as:
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.