Erythrocyte Sedimentation Rate (ESR)

An erythrocyte sedimentation rate (ESR) test is sometimes called a sedimentation rate test or sed rate test. This blood test doesn’t diagnose one specific condition. Instead, it helps your healthcare provider determine whether you’re experiencing inflammation.

An erythrocyte sedimentation rate (ESR) test is sometimes called a sedimentation rate test or sed rate test. This blood test doesn’t diagnose one specific condition. Instead, it helps your healthcare provider determine whether you’re experiencing inflammation. Your doctor will look at ESR results along with other information or test results to help figure out a diagnosis. The tests ordered will depend on your symptoms. The ESR test can also be used to monitor inflammatory diseases.

When you’re experiencing inflammation, your red blood cells (RBCs) cling together, forming clumps. This clumping affects the rate at which RBCs sink inside a tube where a blood sample is placed. The test lets your doctor see how much clumping is occurring. The faster and further the cells sink towards the bottom of a test tube, the more likely it is that inflammation is present. The test can identify and measure inflammation. However, it doesn’t help pinpoint the cause of inflammation. That’s why the ESR test is rarely performed alone.

The ESR test can be used to help your healthcare provider diagnose conditions that cause inflammation, such as:

• Autoimmune diseases
• Cancers
• Infections

A sed rate test may be done when your doctor suspects you have a condition causing inflammation. Sed rate is called a nonspecific test because it does not diagnose specific illnesses but adds to the information about the presence and levels of inflammation.

You might need an ESR test if you experience symptoms of inflammatory conditions such as arthritis or inflammatory bowel disease (IBD). These symptoms can include:

• joint pain or stiffness that lasts longer than 30 minutes in the morning
• headaches, particularly with associated pain in the shoulders
• abnormal weight loss
• pain in the shoulders, neck, or pelvis
• digestive symptoms, such as diarrhea, fever, blood in your stool, or unusual abdominal pain

After collecting your blood, the needle is removed and the puncture site covered to stop any bleeding the blood sample is taken to a lab, where your blood will be placed in a long, thin tube in which it sits to gravity for one hour. During and after this hour, the laboratory professional processing this test will assess how far the RBCs sink into the tube, how quickly they sink, and how many sink Inflammation can cause abnormal proteins to appear in your blood. These proteins cause your RBCs to clump together. This makes them fall more quickly. Your doctor may order a C-reactive protein (CRP) test at the same time as your ESR test. CRP measures inflammation as well, but it can also help predict your risk for coronary artery disease (CAD) and other cardiovascular diseases.