ESR is a test used to detect inflammation in the body. Inflammation could be due to an underlying infection such as stomach infection or cold, autoimmune disease such as arthritis, or even in cancers. So although the ESR increases when there is an inflammation, the test is nonspecific i.e. it does not clearly indicate as to what is the cause of the inflammation.
However, once the cause is ascertained, the gradual decrease in ESR is indicative of improvement in condition. So ESR helps to monitor the disease activity and body’s response to the therapy.
What are erythrocytes? What does sedimentation mean?
The blood contains cells floating in the liquid. So , once blood is collected in a vial (tall thin tube), the solid components of blood start to settle down at the bottom . the red blood cells (erythrocytes) tend to settle down at the bottom of the tube and the rate at which they do so is recorded as the erythrocyte sedimentation rate.
Now, in case of an inflammation, red blood cells tend to clump together and these clumps are more dense than the individual cells so they sediment more rapidly. So the distance the red blood cells fall down to (in mm) in the test tube in the given time (1 hour) increases as indicated by an increased ESR. So high ESR means greater inflammatory response of the immune system.
Reference Ranges for the ESR in Healthy Adults
|Adults||Upper limit of reference range (mm/hr)|
|Age < 50 years|
|Men||0 to 15|
|Women||0 to 20|
|Age > 50 years|
|Men||0 to 20|
|Women||0 to 30|
ESR = erythrocyte sedimentation rate.
Information from Bottiger LE, Svedberg CA. Normal erythrocyte sedimentation rate and age. Br Med J 1967;2:85–7.
ESR may be lower than normal under the following circumstances:
- A disease or condition that increases red blood cell production
- A disease or condition that increases white blood cell production
- Sickle cell anemia (abnormal red blood cells)
ESR may be higher than normal if there is an underlying disease or problem that is causing inflammation, such as:
- Autoimmune disease (a disease that causes your body to attack your own tissues, like lupus)
The ESR is also higher during pregnancy or if you have kidney or thyroid disease.
The family physician takes into account all factors such as medical history, clinical symptoms and other blood parameters before making a clear diagnosis.
So each time you get a CBC done, make sure to look at the ESR levels.