Test Code LAB332 Interleukin-6, Serum
Specimen Required
Collection Container/Tube: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial
Secondary ID
618776Useful For
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
Method Name
Immunoenzymatic
Reporting Name
Interleukin-6, SSpecimen Type
SerumSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
Specimen Type | Temperature | Time |
---|---|---|
Serum | Refrigerated (preferred) | 14 days |
Frozen | 90 days | |
Ambient | 24 hours |
Reject Due To
Gross hemolysis | Reject |
Gross lipemia | Reject |
Gross icterus | Reject |
Reference Values
< 6.4 pg/mL
Cautions
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.
Day(s) Performed
Monday through Saturday
Report Available
1 to 3 daysPerforming Laboratory

Test Classification
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
83529
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
IL6DX | Interleukin-6, S | 26881-3 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
IL6DX | Interleukin-6, S | 26881-3 |