Erythrocyte sedimentation rate (ESR) or ‘sed rate’ is a blood test used to help identify the presence of inflammation in the body. It can be used alongside other tests and medical procedures to monitor and assess inflammatory disease.
While ESR tests are commonly ordered, at YorkTest we recommend using a C-reactive protein (CRP) test to help identify inflammation. This is because ESR is a non-specific measure of inflammation, and can be affected by other variables. Learn more about our Inflammation (CRP) Test here, or read on to learn more about how ESR tests work.
An erythrocyte sedimentation rate (ESR) test measures the rate it takes red blood cells (erythrocytes) in a blood sample to settle at the bottom of a test tube. If your cells fall to the bottom of the tube quickly, this may indicate that you’re suffering from inflammation.
It’s important to note that erythrocyte sedimentation rate tests are not diagnostic tests, and are not a substitute for advice from your doctor. ESR blood tests cannot provide a specific diagnosis of any conditions, and should be taken in conjunction with further tests according to your GP’s advice.
The normal range for red blood cells to settle is sometimes quoted as 0-29mm per hour for women and 0-22mm per hour for men – this is because there can be different ranges depending on the specific lab carrying out the test, test country, population etc. Laboratory normal ranges vary depending on factors such as age and other conditions. A faster than normal rate can be an indicator of inflammation or an inflammatory condition, as red blood cells settle fairly slowly in general.
A blood sample will be taken, and poured into a thin tube. Red blood cells sediment at the bottom of the tube, showing a separation between the cells and plasma. This happens because red blood cells – which make up around 40% of blood content – are more dense than blood plasma. ESR test results are measured in mm per hour, so keeping the tube steady and measuring accurately is essential – it usually takes one hour to get the result.
If your ESR result is in the normal range, this needs to be considered by your doctor alongside other test results according to the symptoms you have.
A slower than normal rate may indicate a potential blood disorder, such as sickle cell anaemia or leukocytosis (the presence of too many white blood cells).
A high ESR test result could be connected to an inflammatory condition, such as:
However, it is important to note that results outside the expected range are not a definite indicator of a medical condition. ESR results can be affected by factors including renal function, age, the size/shape of red blood cells and the level of immunoglobulin and fibrinogen.
The erythrocyte sedimentation rate is typically higher in healthy women than healthy men. Taking certain vitamin supplements and medications – including contraceptive pills, aspirin and Vitamin A – can affect the result. A moderately high ESR test result may also be caused by conditions including anaemia, menstruation or pregnancy.
So, the conclusion is that taking an ESR test alone is not a clear indicator of the state of your health. If you suspect you may have an inflammatory autoimmune disease or other underlying health condition, it’s important to see a doctor as a first step.
In addition to ESR, there are a number of tests for inflammation that doctors can use to aid diagnosis. These include CRP, ferritin, specific autoimmune antibodies, TNF alpha and fibrinogen, which all provide different types of information. An ESR test can be used alongside additional tests to assess an underlying condition, but shouldn’t be used as a standalone marker or test to diagnose healthcare issues.
In many cases, an ESR test may be less useful or specific than other tests. For example, a C-reactive protein (CRP) test is more sensitive and typically generates a more accurate inflammatory indicator. YorkTest’s Inflammation (CRP) Test comes with clear guidance as to whether you need to visit your GP, or whether lifestyle changes are recommended.
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You may wish to take a C-reactive protein (CRP) test, in order to measure the amount of this protein in your blood. This is a more reliable indicator of the presence of inflammation in your body.
If you would like advice on which tests may be right for you, get in touch with our team for more information.