Interleukin 6 (IL-6) Test: Procedure, purpose, results, normal range, cost, price, online booking

Interleukin 6 (IL-6) is an immune protein (specifically pro-inflammatory cytokine and an anti-inflammatory myokine) that is produced by various cells like macrophages, endothelial cells and T cells in response to inflammation. It is an important marker of an active immune system but plays a role in both innate (natural or present since birth) and adaptive (developed after exposure to a pathogen) immunity.

IL-6 test is a blood test that measures the level of this protein in one’s blood sample; although the levels could also be measured in one’s joints and cerebrospinal fluid. IL-6 levels may be elevated in chronic as well as acute conditions, from heart diseases to infections such as COVID-19. The C-reactive protein (CRP) test is another test that is more commonly used to evaluate inflammation.

When is the IL-6 test ordered?
How do I prepare for an IL-6 test?
How is an IL-6 test done?
What do IL-6 test results indicate?
What role does IL-6 play in COVID-19?

Doctors for Interleukin 6 Test

When is the IL-6 test ordered?

An IL-6 test is not ordered often but it might be suggested when a patient has or is suspected of having any of the following conditions:

Infection
Sepsis
Diabetes
Stroke
Cardiovascular disease
Castleman’s disease
Inflammatory bowel disease
Lupus
Rheumatoid arthritis
Other autoimmune disorders

How do I prepare for an IL-6 test?

No preparation is required beforehand for this test. Although fasting is usually not required, your doctor can advise you to in case it’s required in your individual case.

How is an IL-6 test done?

An IL-6 test is usually performed on a blood sample taken from a vein in the arm of the patient. The method used to test the blood is called Enzyme-linked immunosorbent assay (ELISA). You can have the sample collected at home or go to a clinic to have your blood withdrawn.

To obtain the sample, the lab technician will clean an area of your arm with an antiseptic wipe first. Then, they will insert a needle to withdraw a few mL of blood into a sterilized vial.

The process of sample collection is quick and mostly painless but it’s not odd to feel some soreness at the site afterwards.

Appropriate sample handling is essential to get accurate results as IL-6 levels can increase exponentially in the sample if not handled properly.

What do IL-6 test results indicate?

IL-6 is normally not detected in the blood but when it is, one of the previously mentioned conditions is to blame.

The normal range of this protein in blood lies between 0 to 1.8 pg/mL. Several studies have shown that IL-6 is important for the body to mount an immune response against some viral infections. On the other hand, evidence suggests that upregulation of IL-6 could lead to a worsening of disease, leading to a poor prognosis. Given these findings, the usefulness of testing IL-6 levels is still being studied.

What role does IL-6 play in COVID-19?

IL-6 test is now being ordered for many COVID-19 patients. High levels of IL-6 have been noted in cases of severe COVID-19; a meta-analysis shows that the mean serum IL-6 was 56.8 pg/mL in severe COVID-19 patients and 17.3 pg/mL in non-severe COVID-19 patients.

If IL-6, along with other cytokines, is being overproduced in the body, it could result in an interleukin or cytokine storm, which could cause severe damage to the tissues (in this case, lung) and even death. The test may be performed regularly in many cases and helps the doctors with the treatment plan.

Tocilizumab, which is often prescribed in rheumatoid arthritis, may be given to COVID-19 patients based on the results of this test as it has the ability to inhibit IL-6 receptors. Initial research studies have shown that the use of this drug can improve the clinical manifestation of the disease and decreases mortality in COVID-19 patients.

(Read more: COVID-19 and inflammation)