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HomeHealth articleserythrocyte sedimentation rateWhat Is Erythrocyte Sedimentation Rate?

Erythrocyte Sedimentation Rate - Significance and Test Procedure

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An erythrocyte sedimentation rate test is frequently used in conjunction with other tests to diagnose and monitor different disorders. Read on to learn more.

Medically reviewed by

Dr. Rajesh Jain

Published At August 12, 2022
Reviewed AtNovember 8, 2023


The erythrocyte sedimentation rate (ESR) is a blood test that measures the rate at which red blood cells settle in a test tube. Also referred to as ESR, sed rate, sedimentation rate, or Westergren sedimentation rate, this test is used to detect inflammation levels in the body. It is a non-specific indicator of inflammation and is often conducted alongside other tests to diagnose and monitor various diseases. It can serve as a monitoring tool for assessing treatment response in conditions like tuberculosis. There are two methods for measuring ESR, both determining how quickly red blood cells settle in a thin tube. It can aid in diagnosing a range of disorders.

What Are Erythrocytes?

Red blood cells, or RBCs, are known as erythrocytes. They are hemoglobin-filled, biconcave cells that transfer oxygen and carbon dioxide between the lungs and organs. They are produced in the red bone marrow through a process known as erythropoiesis. These mature red blood cells enter the bloodstream.

What Is the Erythrocyte Sedimentation Rate?

ESR tests indicate how quickly erythrocytes (red blood cells) settle at the bottom of a tube containing a blood sample. Red blood cells often settle slowly. A faster-than-normal rate might be an indication of inflammation in the body. Inflammation is a normal aspect of the immune system's reaction. It might be a response to an illness or an injury. Inflammation can also be a symptom of a chronic illness, immunological dysfunction, or another medical issue. It is a test that evaluates the number of particular proteins in the blood in an indirect manner. This measure is related to the level of inflammation in the body.

What Is the Purpose of an Erythrocyte Sedimentation Rate?

If an individual exhibits signs of an inflammatory illness, the doctor may also recommend an ESR. Some of the signs are:

  • Headaches.

  • Fever.

  • Loss of weight.

  • Stiffness of the joints.

  • Pain in the neck or shoulders.

  • Appetite loss.

  • Anemia.

How Is the Erythrocyte Sedimentation Rate Test Performed?

An ESR test involves no extra preparation. A blood draw for an ESR test normally takes only a few minutes. The medical professional drawing the blood sample will begin by cleaning a tiny area of the skin near a vein with an antiseptic solution. Following that, a needle will be placed into the vein, and blood will be taken into a connected tube. The needle is withdrawn when enough blood has been obtained.

The majority of people have no bad effects from an ESR test; however, some may experience some bruises or pain around the site of injection. There are no limits on activities following the test, but one should call their doctor if they detect any indications of infection, such as redness, inflammation, or severe discomfort.

Three stages are:

  1. Rouleaux formation (ten minutes). Red cells stack together like a pair of coins.

  2. The sinking of the rouleaux (40 minutes).

  3. Cell packing (ten minutes).

The ESR is affected by three factors:

  1. Erythrocytes.

  2. Plasma composition.

  3. Mechanical or Technical factors.

What Happens After The Test?

There are several risks associated with a blood test using a needle. Bleeding, infection, bruises, and lightheadedness are some of the symptoms. The patient may feel a tiny sting or pain when the needle pricks their arm or hand. It is possible that the area will be painful afterward.

What Are the Two Types of Erythrocyte Sedimentation Rate Tests?

  1. Westergren Method: Blood is mixed with an anticoagulant and placed in a tall, thin Westergren tube. The distance red blood cells settle in one hour indicates ESR.

  2. Wintrobe Method: Similar to Westergren, blood mixed with an anticoagulant is placed in a slightly shorter, broader Wintrobe tube. Settlement distance in one or two hours indicates ESR.

What Might Affect Erythrocyte Sedimentation Rate Test Results?

The ranges of normal values may differ slightly among laboratories. For men under 50 years old, it may range less than 15 mm/hr (millimeter per hour), and for those over 50 years of age, it is less than 20 mm/hr. For women under 50, it is less than 20 mm/hr, and for women over 50 years old less than 30 mm/hr. For infants, the rate ranges from 0 mm/hr to 2 mm/hr, and from infancy through adolescence, the rate ranges from 3 mm/hr to 13 mm/hr.

What Do Erythrocyte Sedimentation Rate Test Results Mean?

Elevated ESR may be found in:

  • Pregnancy (after the third month).

  • Acute and chronic infections.

  • Rheumatic fever (an illness that can develop as a result of strep throat or scarlet fever that has not been properly treated).

  • Rheumatoid arthritis (an inflammatory condition that affects joints, especially those in the hands and feet).

  • Myocardial infarction (blood flow to the heart muscle is obstructed).

  • Nephrosis (kidney disease in which the body excretes an excessive amount of protein in the urine).

  • Acute hepatitis (an inflammation of the liver).

  • Menstruation.

  • Tuberculosis.

  • Hypothyroidism.

  • Hyperthyroidism.

  • Adults over the age of 60 often have a slightly higher ESR score, owing to decreasing plasma albumin concentrations.

A decreased ESR will be present in:

  • Polycythemia (a condition in which the number of red blood cells in the body increases).

  • Congestive heart failure.

  • Hypofibrinogenemia (this is a rare condition due to a hereditary mutation; one of the two genes involved in the production of fibrinogen is unable to produce a functional fibrinogen glycoprotein due to a hereditary mutation).

  • Abnormal red blood cell formation (poikilocytosis, spherocytes, sickle cells).

What Are the Complicating Factors Affecting the Test Results?

When evaluating the findings of the test rate, the doctor will consider all the complicated conditions. Here are some of these factors:

  • Age.

  • Anemia.

  • Pregnancy.

  • Problems with the kidneys.

  • Thyroid illness is a condition that affects the thyroid gland.

  • Multiple myeloma is a kind of malignancy.

  • Infection.

  • Obesity.

  • Certain medications and supplements.


An ESR test determines how rapidly red blood cells settle into a test tube's container. Additional proteins inside the blood can be caused by inflammation or infection, causing red blood cells to settle quickly. When this occurs, the ESR rises. Inflammatory bowel disease (IBD), arthritis, and lupus are all monitored using ESR testing. If the findings are not within the normal range, it does not always indicate that the person is suffering from a medical problem that has to be addressed. An ESR does not diagnose any diseases, but it can tell whether or not a person has inflammation in their body. If the ESR is abnormal, the clinician would need more details and will likely conduct more blood tests before reaching any diagnosis.

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Dr. Rajesh Jain

General Practitioner


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