Interleukin (IL-6) Test: Procedure, Uses, Price and Result

IL-6 is the interleukin-6, which is a cytokine that is released during the immune response. IL-6 is responsible for the development of acute phase response. This acute phase response leads to systemic inflammation. So, IL-6 acts as a marker for inflammation. 

During the immune response, three important cytokines are going to be released, which can develop the inflammatory cascade. 

1. The first one is IL-1 (interleukin-1) which is responsible for the development of hyperthermia that is fever. 
2. The second one is IL-6, which plays a key role in the inflammatory cascade.
3. The third one is the TNF-alpha (tumor necrosis factor-alpha) 

These three cytokines play a crucial role in the immune response and they are pro-inflammatory mediators. 

What is The Interleukin Test Means? 

The Interleukin test plays a crucial role in the assessment of the severity of information, so elevated levels of IL-6 indicate progressive information, which gives an early sign to control the inflammation. 

For instance, in COVID-19, the immune response is going to be stimulated, which results in the release of cytokines. These cytokines may result in a cytokine storm, where excessive stimulation of T cells along with the release of cytokines may cause systemic inflammation. 

In such conditions, elevated levels of il6 can be recognized within the patient, which should be controlled to prevent the further progression of the inflammation.

Interleukin Test Uses

This test is primarily used to detect the presence of Interleukin 6, but it is also used as a diagnostic tool in the early diagnosis of a variety of health conditions. Interleukin-6 can help assess a person who has an inflammatory disorder, such as 

• Lupus 
• Rheumatoid arthritis 
• Sepsis
• Diabetes
• Stroke
• Cardiovascular disease.

Which Conditions are Elevated?

The elevated IL-6 levels are associated with the immune response. It can lead to the stimulation of immunity, which produces systemic inflammation. IL-6 levels are raised in a variety of diseases and have been linked in some cases to an increased risk of disease onset or a worsened prognosis. 

Conditions such as rheumatoid arthritis, lupus and other autoimmune illnesses, infections, sepsis, certain malignancies, diabetes, cardiovascular disease, and stroke are associated with inflammation, where the il6 levels are elevated within the plasma. 

It can also be elevated in a few of the inflammatory conditions like asthma, and inflammatory bowel disorder, so wherever there is systemic inflammation, there may be an elevated level of il6, which shows the severity of the inflammation within the body. 

Thus, in PJI, sepsis, COVID-19, and RA, IL-6 serum levels have been examined and reported to predict severity and response to IL-6 targeted therapy.

When Will the Interleukin Test Be Ordered?

The IL-6 test is not commonly ordered. The most typically ordered test to evaluate inflammation is C-reactive protein (CRP), although IL-6 may be ordered in combination with or after a CRP test when a person exhibits signs and symptoms of an inflammatory disorder or infection and a health care provider needs more details.

The following conditions require an IL-6 test:

• When a patient is suspected of having sepsis or septicemia
• Rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, and even IBD are all auto-immune diseases (inflammatory bowel disease)
• Cancers of certain types
• Localized infections like periodontitis
• Systemic infections like COVID-19

How is the Interleukin Test Done? 

This test is done by collecting blood from the veins in the test tube which is coated with the EDTA such that we can inhibit the coagulation and separate the plasma. But after the collection of the blood sample, it should be immediately centrifuged so that the plasma can be separated. 

The supernatant liquid is the plasma which is stored for the analysis of the IL-6. The centrifugation should be done within 30 minutes after the collection of the blood sample. So if the plasma is separated after 30 minutes, it may cause analytical errors in the il6 test. 

Once the plasma is going to be separated, it should be immediately refrigerated and, better, it should be stored in a frozen form. We should freeze the sample within 24 hours in order to eliminate the pre-analytical errors. 

Interleukin 6 Test Price

The test price varies from Rs 2500 to Rs 4000. The price changes from laboratory to laboratory and city to city. 

What are the Normal Values? 

Generally, IL-6 is not significantly detected within the systemic circulation. 

That's why normal levels of il6 can be considered as 0.007 ng/ml or 7 pg/ml, but the normal level can also be considered up to 18 nanograms per ml. 

There will be slight variability in the normal levels according to the analysis. Up to 18 nanograms per ml, can be considered as a normal level. But sometimes the slight elevation of IL-6 values may not be correlated with systemic inflammation. So always IL-6 levels should be correlated with the clinical symptoms within the patient. 

That's why in a few of the studies, a cut-off value is going to be given to the il6 value. Generally, the cutoff value is considered at 80 nanograms per ml. This cut-off value indicates the severity of inflammation.

What do the Interleukin Test Results Mean?

So whenever this IL-6 value is greater than 18 nanograms per ml, it shows progressive information which should be immediately treated. 

But IL-6 is not a specific biomarker for the information, even if it indicates the inflammation within the body but it is not indicating a particular type of information, whether it is an autoimmune disorder or infection, sepsis or cancer.

In all these conditions, IL-6 may be elevated so it will not specify a particular type of inflammatory response within the body. 

Generally, elevated levels of IL-6 indicate an inflammatory response, which should be compared with the other biomarkers in order to identify a specific inflammatory disorder. For example, in the immune response, the IL-6 levels are elevated along the elevator levels of CRP. 

Similarly, whenever IL-6 levels are normal, we cannot rule out the inflammation because sometimes even IL-6 levels are normal, other inflammatory biomarkers may be elevated, which indicates the inflammation within the patient.