Test Id : IL6DX
Interleukin-6, Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluating patients with suspected chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, or inflammatory bowel disease
Evaluating patients with Castleman disease
Evaluating patients with suspected systemic infection
Evaluating patients with suspected localized infection, specifically prosthetic joint infection
Assisting in identifying severe inflammatory response in patients with confirmed COVID-19 illness to aid in determining the risk of intubation with mechanical ventilation, in conjunction with clinical findings and the results of other laboratory testing
Highlights
Fact sheets for this emergency use authorization (EUA) assay can be found at the following links:
-For healthcare providers: www.fda.gov/media/142598/download
-For patients: www.fda.gov/media/142599/download
Method Name
A short description of the method used to perform the test
Immunoenzymatic
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Cytokine
Cytokines
IL-6
Systemic inflammation
IL6
IL6DX
Specimen Type
Describes the specimen type validated for testing
Serum
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Collection Container/Tube: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Ambient | 24 hours | ||
| Frozen | 90 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluating patients with suspected chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, or inflammatory bowel disease
Evaluating patients with Castleman disease
Evaluating patients with suspected systemic infection
Evaluating patients with suspected localized infection, specifically prosthetic joint infection
Assisting in identifying severe inflammatory response in patients with confirmed COVID-19 illness to aid in determining the risk of intubation with mechanical ventilation, in conjunction with clinical findings and the results of other laboratory testing
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Interleukin 6 (IL-6) has important roles in both innate and adaptive immunity.(1) IL-6 can be produced by a variety of different cell types, including macrophages, endothelial cells, and T cells. This production can be initiated in response to microbial invasion or other cytokines, such as tumor necrosis factor. As part of the innate immune system, IL-6 acts on hepatocytes to induce expression of C-reactive protein (CRP), fibrinogen, and serum amyloid A, also known as the acute phase response. Within the adaptive immune response, IL-6 plays a key role in activating antibody-producing B cells to proliferate, leading to an enhanced antibody response.
Concentrations of IL-6 are elevated in patients with infection, sepsis, and septicemia. During inflammatory conditions, the concentration of IL-6 can increase severalfold, highlighting its clinical relevance as a major alarm signal in response to infections (sepsis/septicemia), inflammation, autoimmunity, and cancer, including Castleman disease. In addition, IL-6 concentrations appear to correlate with the severity of sepsis, as defined by clinical and laboratory parameters.(2) Elevations in IL-6 also appear to be associated with more localized infections, such as prosthetic joint infections (PJI).(3) A recent meta-analysis demonstrated that IL-6 had improved diagnostic accuracy for PJI compared to CRP, erythrocyte sedimentation rate, and white blood cell counts. IL-6 is also elevated in numerous chronic inflammatory disorders, including rheumatoid arthritis (RA), systemic lupus erythematosus, ankylosing spondylitis, and inflammatory bowel disease.(4)
There is evidence that IL-6 is involved in the pathogenesis of certain chronic inflammatory disorders. Tocilizumab, an antibody that blocks IL-6 function by binding to the IL-6 receptor, has been approved for the treatment of RA. In a randomized trial, 50% to 60% of patients receiving tocilizumab and methotrexate showed improvement in clinical signs and symptoms of RA, compared to only 25% of patients receiving methotrexate alone.(5) Siltuximab, a monoclonal antibody against IL-6, is also sometimes used to treat Castleman disease. However, the presence of Siltuximab may interfere with some IL-6 assays, leading to the proposed use of CRP as a surrogate marker to monitor Siltuximab efficacy.(6-8)
IL-6 has also been shown to be elevated in COVID-19 patients. There is some indication that patients with more severe disease may develop elevated circulating IL-6. The significance of this finding is still being elucidated, including whether monitoring of circulating IL-6 levels can help with patient management, prognosis, or response to treatment.(9,10)
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
< 6.4 pg/mL
Interpretation
Provides information to assist in interpretation of the test results
Elevated concentrations of interleukin 6 may indicate an ongoing inflammatory response and could be consistent with a systemic infection, localized infection, or chronic inflammatory disease.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Interleukin 6 (IL-6) is a nonspecific marker associated with an inflammatory response and is not diagnostic for any specific disease or disease process. Elevated concentrations of IL-6 must be interpreted within the clinical context of the patient.
Normal concentrations of IL-6 do not exclude the possibility of an ongoing inflammatory process.
Interleukin-6 concentrations may be elevated in patients receiving IL-6 receptor inhibitors, such as tocilizumab, due to receptor blockade and reduced clearance of IL-6. As a result, IL-6 concentrations are not reflective of adequate tocilizumab response. Additionally, patients receiving anti-IL-6 monoclonal antibodies such as siltuximab may also exhibit interference in IL-6 measurements. For both patient cohorts, a more reliable assessment of IL-6-mediated inflammation can be obtained by measuring downstream acute-phase reactants, such as C-reactive protein.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Scheller J, Chalaris A, Schmidt-Arras D, Rose-John S. The pro- and anti-inflammatory properties of the cytokine interleukin-6. Biochim Biophys Acta. 2011;1813(5):878-888
2. Tsalik E, Jaggers B, Glickman SW, et al. Discriminative value of inflammatory biomarkers for suspected sepsis. J Emerg Med. 2012;43(1):97-106
3. Berbari E, Mabry T, Tsaras G, et al. Inflammatory blood laboratory levels as markers of prosthetic joint infection: a systematic review and meta-analysis. J Bone Joint Surg Am. 2010;92(11):2102-2109
4. Gabay C: Interleukin-6 and chronic inflammation. Arthritis Res Ther. 2006;8 Suppl 2:S3
5. Smolen JS, Beaulieu A, Rubbert-Roth A, et al. Effect of interleukin-6 receptor inhibition with tocilizumab in patients with rheumatoid arthritis (OPTION study): a double-blind, placebo-controlled, randomized trial. Lancet. 2008;371(9617):987-997
6. Yoshizaki K, Murayama S, Ito H, Koga T. The Role of interleukin-6 in Castleman disease. Hematol Oncol Clin North Am. 2018;32(1):23-36. doi:10.1016/j.hoc.2017.09.003
7. Sarosiek S, Shah R, Munshi NC. Review of siltuximab in the treatment of multicentric Castleman's disease. Ther Adv Hematol. 2016;7(6):360-366. doi:10.1177/2040620716653745
8. Chen F, Teachey DT, Pequignot E, et al. Measuring IL-6 and sIL-6R in serum from patients treated with tocilizumab and/or siltuximab following CAR T cell therapy. J Immunol Methods. 2016;434:1-8. doi: 10.1016/j.jim.2016.03.005
9. Gubernatororova EO, Gorshkova EA, Polinova AI, Drutskava MS. IL-6: Relevance for immunopathology of SARS-CoV-2. Cytokine Growth Factor Rev. 2020;53:13-24
10. Ashrafzadeh-Kian S, Campbell MR, Jara Aguirre JC, et al. Role of immune mediators in predicting hospitalization of SARS-CoV-2 positive patients. Cytokine. 2022;150:155790. doi:10.1016/j.cyto.2021.155790
Method Description
Describes how the test is performed and provides a method-specific reference
The Access Interleukin-6 (IL-6) assay is a simultaneous one-step immunoenzymatic (sandwich) assay. A patient sample is added to a reaction vessel along with the paramagnetic particles coated with mouse monoclonal anti-human IL-6, blocking reagent, and the alkaline phosphatase conjugate.
After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then, the chemiluminescent substrate is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of IL-6 in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.(Instruction manual: Access IL-6 Instructions for Use, Beckman Coulter, Inc; 10/2020)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Saturday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test has received Emergency Use Authorization (EUA) by the US Food and Drug Administration and is used per manufacturer’s instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
83529
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| IL6DX | Interleukin-6, S | 26881-3 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| IL6DX | Interleukin-6, S | 26881-3 |