ESR Test (Erythrocyte Sedimentation Rate)

The erythrocyte sedimentation rate (ESR) blood test, also called a sedimentation rate or sed rate, is used to detect diseases associated with inflammation.

It is useful in detecting inflammation diseases like:

• Infection
• Autoimmune disease
• Heart disease
• Arthritis

This test is also used to evaluate the nonspecific activity of infections, inflammatory states, autoimmune disorders, and plasma cell dyscrasias.

What is Erythrocyte Sedimentation Rate (ESR)?

The Erythrocyte Sedimentation Rate, also known as “ESR” or “SED rate,” is a blood test done to measure how quickly erythrocytes (red blood cells) fall. The test is performed to help determine the amount of inflammation occurring in the body.

The blood is drawn from the patient and placed in a tall, thin, upright test tube. The blood is then treated so it will not clot, and the red blood cells will separate from the plasma. A lab specialist will monitor the rate at which the red blood cells fall to the bottom of the tube over the course of an hour. It’s called a “Sedimentation Rate” because it measures the rate at which the erythrocytes sediment.

What is a typical ESR Test Result?

Typical ESR rates:

Males

• 0 - 50 years old: 0 - 15 mm/hour
• 50+: 0 - 30 mm/hour

Females

• 0 - 50 years old: 0 - 32 mm/hour
• 50+: 0 - 40 mm/hour

Higher sedimentation rates are typically seen in older adults as inflammation becomes more common with age. However, if your ESR rates are outside of the average range for your age, we suggest getting additional tests to confirm inflammation and help pinpoint the cause.

Sedimentation rates higher than 100 mm/hr are typically caused by an active disease. Some diseases that commonly cause high ESRs include:

• Arthritis
• Asthma
• Autoimmune Disease
• Blood Disease
• Diabetes
• Heart Disease
• Hepatitis
• Peptic Ulcer
• Tuberculosis

Certain conditions may affect the ESR observed. These conditions include:

• Being Female
• Certain Medications
• Menopause
• Menstrual Cycle
• Menopause
• Obesity
• Old Age
• Pregnancy
• Recent Surgery

Why does ESR increase with Inflammation?

When inflammation and injuries occur, certain proteins are secreted. These proteins will bind to the membrane of the erythrocytes, causing them to increase in density and fall at a higher rate than average.

Some of the proteins that may affect the red blood cell sedimentation rate include:

• Fibrinogen: A necessary protein for blood clotting
• C-Reactive Protein (CRP): A protein released into the blood after tissue injury, at the beginning of an infection, during an autoimmune disease, or other causes of inflammation
• Immunoglobulins: Antibody proteins that the body makes to fight off infections
• Acute-phase proteins: Proteins that increase in response to injury or inflammation

How is the Test performed?

Our blood labs perform the Westergren Sedimentation Rate, which requires at least 2 mL of blood. The blood is placed in a tall, thin tube. A lab technician then monitors the rate at which erythrocytes fall over the course of an hour. For the Westergren Sedimentation Rate, optimum results are produced from blood that is less than 2 hours old, however blood can be tested for up to 24 hours after collection, given that it has been refrigerated.

How do I Need to Prepare for the Test?

Preparation for the test is minimal. Though there is competing research on the topic, we do not require that you fast for the test. Even with the elevated glucose levels that may be present from eating or drinking before getting your blood drawn, the difference between the ESR of fasted blood and non-fasted blood isn’t statistically significant enough for us to require fasting. However, if you worry that non-fasted blood may result in undesired results, consider fasting before taking this test.

Who should take the ESR test?

You may want to take this test if you have any symptoms of an inflammatory disease. Symptoms include

• Headache
• Joint pain/swelling
• Fever
• Weight loss

The test is typically ordered to monitor the progression of a disease, or to confirm the diagnosis of certain inflammation-causing diseases. Please note that this test cannot and does not determine a specific disease; it only indicates that there is inflammation present in the blood. More tests are needed to determine the specific cause of inflammation, and ESR tests are not typically ordered for diagnosis but rather monitoring.