ESR Test

Erythrocyte sedimentation rate (ESR) test is a blood test that measures the rate at which erythrocytes (red blood cells) from blood samples descend and settle down a test tube.

Under normal circumstances, erythrocytes take a long time to settle. However, in the presence of inflammation or cell damage, erythrocytes clump together, making them bulky, which increases their rate of settling.

When erythrocytes settle rapidly, the ESR value increases. 

ESR values ​​higher or lower than the normal indicate the presence of the disease.

ESR is not a diagnostic test. That is, it does not help in diagnosing any particular disease. It is a simple, cost-effective and screening test that indicates the presence or absence of inflammatory diseases anywhere in the body. 

In addition to the ESR, other tests should also be done to identify the exact cause of the swelling.

ESR is performed in individuals who are suspected of having an inflammatory condition, for example, arthritis, which causes joint pain and swelling, or inflammatory bowel disease, which causes symptoms of the digestive tract.

ESR is usually recommended in the presence of the below symptoms:-

• Unexplained weight loss
• Headache
• joint stiffness
• loss of appetite
• Muscle pain
• Fever
• Anaemia
• Shoulder and neck pain
• Pelvic pain

Two methods are used to measure ESR in blood.

These are as follows:-

• Westergren Method

This is the most common ESR method. In this type of test, blood is drawn into a Westergren-Katz tube until the level of blood reaches 200 millimeters (mm).

The tube is stored upright and left to settle at room temperature for one hour. The distance between the top of the blood mix and the sedimentation of RBCs is measured.

• Wintrobe Method

The Wintrobe method is similar to the Westergren method, except the tube used is 100 mm longer and thinner.

A disadvantage of this method is that it is less sensitive than the Westergren method.

No preparation is required for this test.

Before undergoing the test, make sure you inform your doctor about any prescription or over-the-counter medicines, vitamins, herbs or supplements that you take.

The doctor should also be informed about any bad habits like food and alcohol taken before the test. Also, information about any existing conditions such as pregnancy or ongoing periods should be given for proper evaluation of your blood report.

This is a common test, which takes about less than five minutes. A phlebotomist collects a blood sample from a vein in your arm by inserting a small needle.

A small amount of blood is then drawn into a sterile vial or a test tube. When the needle goes into the vein, a momentary pricking pain may be felt.

With this test, there is minimal risk of injection site pain, dizziness and bruising. However, most of the time, these symptoms quickly disappear. Rarely, infection may occur at the site of blood drainage.

Erythrocyte Sedimentation Rate, test results measure the amount of plasma at the top of the test tube after one hour of sedimentation. ESR is expressed in terms of millimetres per hour.

An ESR value higher than normal, indicates the presence of an inflammatory disease. Some common causes of a moderately elevated ESR include:-

• Kidney disease
• Infection
• Pregnancy
• Anaemia
• Ageing
• Multiple myeloma

High ESR value can also be result of autoimmune disorders like:-

• Type 1 diabetes
• Rheumatoid arthritis
• Rheumatic fever
• Inflammatory Bowel Disease (IBD)
• Vasculitis

A lower ESR value indicates the presence of blood related disorders, such as:-

• lack of red blood cells
• Leukocytosis
• An increase in the number of white blood cells that are higher than normal.
• Polycythemia

Interpretation of test results varies based on parameters such as age, gender, method used to conduct the test and medical history of the individual. Moderately elevated ESR values ​​do not confirm the presence of inflammation, as they can also be caused by factors such as pregnancy.

Some medicines can alter the ESR value, and your doctor should be informed about the usage of such medicines. such as :-

• aspirin,
• oral contraceptives,
• methyldopa,
• dextran (dextran),
• theophylline,
• penicillamine (penicillamine),
• procainamide,
• Cortisone and Vitamin A

Medicines such as these can increase ESR.

Whereas quinine and steroids can lower ESR.

Sometimes a repeat ESR with time intervals between tests is recommended. This is done to monitor the progression of the disease and the effectiveness of the treatment.

An upward trend in ESR indicates increased inflammation or an inadequate response to treatment.