Erythrocyte Sedimentation Rate (ESR)

What is the erythrocyte sedimentation rate?

The sedimentation rate shows, in millimeters, how far red blood cells settle within one hour when blood that has been prevented from clotting is left to stand in a thin, upright tube. It is commonly known by the short name ESR or "sed rate". The classic measurement method is the Westergren method; today, automated analyzers calibrated to this method are also widely used.

When there is inflammation in the body, the liver produces more of certain proteins, such as fibrinogen. These proteins cause red blood cells to stack on top of one another and clump together, and the clumps settle faster. For this reason, although the ESR does not show where the inflammation is, it provides indirect, nonspecific information about its presence.

When is the ESR test ordered?

The ESR is usually ordered together with CRP when an inflammatory disease is suspected. It is a valuable test especially for helping to diagnose certain rheumatic diseases and for monitoring the response to treatment. Because it cannot establish a diagnosis on its own, the result is always considered together with other findings. In treatment monitoring, the change in the value over time is more meaningful than a single measurement.

• Unexplained fever, weight loss or prolonged weakness
• Joint pain, swelling and morning stiffness
• Pain and stiffness around the shoulders and hips (suspected polymyalgia rheumatica)
• New-onset pain in the temples and jaw pain when chewing in older adults (suspected giant cell arteritis)
• Monitoring of inflammatory diseases such as rheumatoid arthritis
• Treatment monitoring in bone or joint infections

How should you prepare for the ESR test?

You do not need to be fasting in the morning for an ESR measurement; blood can be drawn at whatever time of day suits you. Pregnancy, anemia and some medicines can affect the result, so it is helpful to mention these before the sample is taken. A recent cold or another infection can also temporarily raise the value.

Blood is drawn from a vein in the arm into a tube containing a suitable anticoagulant. For a reliable result, it is important that the measurement is made within a few hours of the sample being taken. Because the tube must stand upright without being shaken throughout the measurement, the procedure is carried out in the laboratory under standard conditions. You do not have to go to a healthcare facility to give blood; a nurse can come to your home or workplace.

What does the ESR result mean?

A high ESR may be associated with infections, inflammatory rheumatic diseases such as rheumatoid arthritis, polymyalgia rheumatica, giant cell arteritis, tissue damage and certain types of cancer. Very high values may also lead the doctor to investigate diseases that affect blood proteins, such as multiple myeloma. However, pregnancy, anemia, kidney disease, older age and female sex can also raise the ESR slightly.

A low ESR usually does not indicate a problem; conditions with a high red blood cell count, cell shape disorders such as sickle cell anemia, or a very high white blood cell count can lower the value. A result within the normal range does not always rule out disease, either. The values considered usual vary by age, sex and laboratory; the ranges set by the testing laboratory for women and men are shown on this page. Your doctor, who evaluates your symptoms, examination findings and other tests such as CRP together, decides what your ESR value means.