ESR

What is being tested?
ESR is an indirect measure of the degree of inflammation present. It measures the rate at which red blood cells settle when blood, made unclottable, is placed in a graduated tube in an upright position. The result, expressed in mm/h, is the distance between the initial level of the blood and the top of the column of settled red cells after 1 and 2 hours. ESR is affected by plasma factors such as the concentration of large molecules (mainly immunoglobulins, fibrinogen, acute-phase proteins, etc.), red cell factors such as the number and size of red blood cells, and physiological factors such as age or pregnancy.

How is the sample collected for testing?
The sample is taken from a vein in the arm.

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
ESR is a useful, easy and inexpensive test, but it is completely non-specific; it has long been used to assess conditions associated with acute and chronic inflammation, including infections, autoimmune diseases and cancers. ESR is not a specific test, as it gives no information about the site involved in the inflammatory or infectious process or about the type of inflammatory disease present (acute or chronic); in addition, ESR can be affected by various factors unrelated to inflammation. ESR should therefore never be considered on its own (high risk of false positives) but must be assessed together with other markers of inflammation, such as the white cell differential, CRP, fibrinogen, serum protein electrophoresis, etc.

ESR can be used specifically to confirm the diagnosis of two particular inflammatory diseases, temporal arteritis and polymyalgia rheumatica, for which ESR is also used to follow their course and monitor treatment.

When is it requested?
ESR is ordered, together with other laboratory tests, when there are symptoms suggesting an ongoing inflammatory process. In temporal arteritis or polymyalgia rheumatica, there may be headache, neck or shoulder pain, pelvic pain, anaemia, unexplained weight loss and joint stiffness. Many other conditions can cause temporary or permanent changes in ESR.

Because ESR is non-specific and affected by many other factors, the result must be considered together with the clinical signs, the patient’s medical history and other laboratory results. A raised ESR on its own, without specific symptoms, does not give enough information for a diagnosis.

Once a diagnosis has been made, however, it can be useful to repeat the test periodically to follow the course of the disease.

What does the test result mean?
A diagnosis cannot be based solely on the ESR result; it must be accompanied by the patient’s clinical signs and other laboratory findings.

A moderate increase in ESR may be seen during infection, inflammation of any origin and anaemia, but also during pregnancy or in older age.

A common cause of a raised ESR is anaemia, when associated with changes in red cell shape; in some cases, however, such as sickle cell anaemia, ESR is decreased. In multiple myeloma or Waldenström’s macroglobulinaemia, where plasma immunoglobulin levels are greatly increased, and more generally in many blood cancers, a typical increase in ESR is seen even without inflammation.

Although a low ESR has little clinical significance, it may occur with polycythaemia and extreme leucocytosis.

Is there anything else I should know?
ESR and C-reactive protein are both markers of inflammation. CRP generally changes earlier than ESR as the activity of inflammation changes; in addition, CRP levels are not affected by factors unrelated to inflammation, as ESR is; for this reason CRP is often considered a better marker of inflammation than ESR. Nevertheless, because it is easy and inexpensive, ESR is still widely used as a first-line test when inflammation is suspected.

Women tend to have higher ESR values, partly because menstrual periods and pregnancy can cause temporary increases.

1. What other tests are usually ordered together with ESR?
2. What can changes in the ESR value mean?

1. What other tests are usually ordered together with ESR?
ESR is usually ordered together with other markers of inflammation, such as the white cell differential, CRP, fibrinogen, serum protein electrophoresis, etc. When autoimmune disease is suspected, ESR may be ordered together with other second-line tests such as anti-DNA autoantibodies, ANA, ENA, rheumatoid factor, Waaler-Rose, etc.

2. What can changes in the ESR value mean?
ESR is a marker of inflammation whose values correlate well with the activity of the ongoing inflammation.