Erythrocytes are red blood cells in blood (RBCs). Rate of sedimentation of erythrocytes is a measure of how fast red blood cells separate from rest of the blood. The settling down of red blood cells in a tube (Westergren tube)...
What is erythrocyte sedimentation rate?
Erythrocytes are red blood cells in blood (RBCs). Rate of sedimentation of erythrocytes is a measure of how fast red blood cells separate from rest of the blood. The settling down of red blood cells in a tube (Westergren tube) under the influence of gravity is called sedimentation.
What is ESR test and why is it done?
Normally, erythrocytes settle slowly but if there is some issue in the body, the sedimentation rate of erythrocyte is affected. Red blood cells start clumping together in case of inflammation in the body, and start settling down at a faster pace as compared to normal circumstances.
ESR test is a hematology test (blood test) performed in order to check for inflammation in the body. Reasons for inflammation can be multiple and to identify the root cause of increased inflammation, further diagnosis is required.
The Westergren method for ESR blood testing is used all around the world due to its reproducibility over decades. Westergren method is approved by International Committee for Standardization in Hematology (ICSH).
When should I get an ESR blood test done?
It is for the doctor to diagnose the need for getting an ESR test. After examination of all symptoms, if the doctor feels the need for ESR test due to suspected inflammation in the body, he/she will prescribe this test.
Inflammation is an indicator of some disease, underlying condition or malfunction of some organ or body system.
The root cause of inflammation in body can only be known after further diagnosis but here are some of the commonly diagnosed causes of inflammation in the body:
- Autoimmune disorder
- Tumor in body
- In case of infections
What is the procedure of ESR test?
The procedure of ESR test is quite simple. The tube used for ESR test is called Westergren tube, which is made up of either glass or plastic.
Following steps are performed in ESR test:
- A healthcare professional takes required amount of blood from vein in arm of an individual.
- The blood sample is mixed with an anticoagulant, such as Sodium citrate, so as to prevent clotting of blood.
- The blood sample is poured into an upright tube and the tube is inserted into vacuum, left undisturbed.
- After one hour the tube is observed to check the distance in mm covered by red blood cells towards the bottom of tube.
- The rate of sedimentation is reported in mm/hour.
How to prepare for ESR test?
There is no preparation required before getting an ESR test. It may also be noted that if you have to give blood sample for some other hematology test, fasting maybe required. Consult your doctor regarding this.
What are the causes of high ESR?
As mentioned earlier, High ESR value depicts inflammation occurring in the body due to some reason. Red blood cells have negative charges on their surface. When there is inflammation in body, some positively charged proteins get attached to the surface of RBCs, neutralizing negative charge, resulting in clumping of red blood cells. It is because of clumping, the weight of RBCs increases and they tend to settle faster towards the bottom. When RBCs settle faster, it results in high ESR value in report.
How to read ESR test report?
ESR result will have value reported in mm/hour.
Diagnostic labs write the normal range for ESR value on the report itself. The normal value range varies from lab to lab. It also depends on gender and age. For instance, females have a higher ESR normal value as compared to males. Normal ESR value also increases with age.
Slightly high or low ESR value is not alarming, and can be due to environmental factors.
Following are normal values of ESR test as per Westergren method (rough estimates, for proper information consult your doctor):
For children, ESR value should be
