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Erythrocyte sedimentation rate (ESR) is s blood test that checks for inflammation in the body. When you have an infection, injury and several other conditions, such as blood disorders, certain cancers, and immune system disorders, your immune system responds, leading to inflammation.

Erythrocytes are also called red blood cells. An erythrocyte sedimentation rate requires a blood sample. The healthcare professional will put the blood sample in a tall, thin test tube to measure how quickly the red blood cells sink or settle at the bottom of the tube. Usually, the red blood cells settle gradually, but inflammation causes red blood cells to stick together, forming clumps. These clumps are heavier than the single cell, so they settle faster.

If your red blood cells settle faster than they should, you may have a medical problem that causes inflammation. The speed of settling can indicate the level of inflammation. A faster ESR rate means higher levels of inflammation, but only an ESR test cannot offer a definitive diagnosis of the cause of the inflammation.

Other names for the ESR test are Westergren sedimentation rate and SED rate sedimentation rate.

What is ESR used for?

The ESR test is often used alongside other tests to diagnose conditions that result in inflammation, such as infection, vasculitis, inflammatory bowel disease and arthritis. The test can also help monitor an existing health condition.

Why is an ESR test necessary?

Your doctor may order the ESR test if you present symptoms of a condition that results in inflammation. These symptoms usually depend on the condition but often include the following:

What happens during an ESR?

The healthcare professional will draw blood with a small needle from a vein in your arm. After inserting the needle, they will collect a small amount of blood for the test into a vial or tube. The needle may cause a slight sting as it goes in and out. The blood collection often takes less than five minutes.

Do I need to prepare for an ESR?

No special preparation is necessary for ESR, but your healthcare professional may inform you to fast for several hours before the blood draw if you need other tests. You will get special instructions if necessary.  

What are the risks of ESR?

The risk of having an ESR is small. You may only feel slight pain or bruising at the injection site, but this quickly clears.

What does the result mean?

Your doctor will interpret your ESR result while considering your symptoms, medical history and other test results. Only an ESR test cannot diagnose an inflammation-causing condition.

A high ESR result may indicate the following conditions that cause inflammation.

A low ESR result which means the red blood cells settle slower than normal, may result from conditions like:

An ESR test result outside the normal range doesn’t always indicate a medical condition that requires treatment. For example, ageing, a menstrual cycle, pregnancy, exercise, obesity and drinking alcohol regularly can affect ESR results.

Some supplements and medicines may affect your results, so ensure you inform your provider if you are taking any supplements or medicines.

Other facts about ESR

Since the ESR test doesn’t diagnose a specific condition, your doctor may also order other tests. Your ESR result may also be normal if you have a condition that causes inflammation. ESR and C-reactive protein (CRP) tests are usually done together to get more information.

Private Blood Tests London offers the ESR test alongside other tests to determine if you have inflammation. You can visit our clinic or call 02071830244 to schedule your ESR test.