ESR blood test: what the erythrocyte sedimentation rate may show

For this test a tube of blood is taken. It measures how fast red blood cells settle in that tube, expressed in mm per hour. When there is inflammation in the body, certain proteins in the blood increase, making red blood cells clump together and settle faster. How fast red blood cells settle can therefore say something about a possible inflammatory response.

For an ESR test, also written as the sed rate or erythrocyte sedimentation rate, a sample is drawn from a vein in your arm and placed in a tall, thin tube. The test measures how fast the red blood cells sink, which is why it is sometimes described as how quickly red blood cells settle. No special preparations are usually needed before an ESR test. A high ESR may be linked to a number of conditions, including infection, autoimmune conditions, and giant cell arteritis, but a raised result alone does not point to one cause. ESR results are often read together with the C-reactive protein (CRP) value. Your ESR levels are best interpreted by your GP alongside your symptoms. Related markers such as white blood cell count, ferritin, and rheumatoid factor can give extra context, and VitalCheck inflammation-related panels group these markers together.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

ESR is a non-specific marker. A slightly raised result can have many causes and is best viewed in context. For many adults a normal value is roughly below 15 to 20 mm per hour, although reference values vary by laboratory, age, and sex. A raised ESR can be associated with infections from bacteria or viruses, with tumours, and with autoimmune conditions. ESR is often viewed together with C-reactive protein (CRP). Discuss your results with your GP.

Some people have their ESR measured for unexplained fever, joint pain, or muscle aches, or to follow up on a previously diagnosed condition. Because ESR does not indicate where an inflammation is located, the result is usually combined with other blood values and your symptoms. Your GP can help you decide whether further steps are needed.