Interleukin-6 Test

Inflammatory Cytokine Biomarker for Predicting
COVID Progression & Severity

Clinical Information

Interleukin-6 or IL-6 is a member of the cytokine family, with a pivotal role in the activation and regulation of
immune response. Cytokines play several important roles, but its significance to the immune system has been
given much importance recently: it triggers “inflammatory cascade” wherein a coordinated and sequential
immune response is activated.

The Role of IL-6 in COVID-19 Patient Management

Some recent literature discussed the pathogenesis of cytokine release syndrome (CRS) in severe COVID-19
patients. CRS is a systemic inflammatory response that can be caused by infection, some drugs, and other
factors, characterized by a sharp increase in pro-inflammatory cytokine level, like IL-6.
Interleukin-6 is a key molecule in CRS and is now being tested to monitor its response in COVID patients. It can
be used as predictor for a more immediate diagnosis of patients with higher risk of disease deterioration. Given
the high levels of cytokines induced by SARS-CoV-2, a timely treatment to reduce lung damage via inflammation
is critical to improving recovery rates and reducing mortality.

Other Clinical Applications of IL-6 Test

Evaluation of patients with:

  • Suspected systemic infection
  • Suspected localized infection, specifically prosthetic joint infection
  • Suspected chronic inflammatory disorders, such as rheumatoid arthritis, systemic ankylosing spondylitis, or
    inflammatory bowel disease

Test Information

Analytical Method
The interleukin-6 (IL-6) cytokine assay employs an in vitro enzyme-linked immunosorbent assay for the quantitative
measurement of human IL-6 in serum. This involves a sandwich immunoassay format where captured antibodies
are coated in a single spot at the bottom of each well. The assay employs detection antibodies conjugated with
chemiluminescent labels.

Elevated concentrations of Interleukin-6: >7 pg/ml may indicate an ongoing inflammatory response, which could
be consistent with a systemic infection or chronic inflammatory disease.
For COVID-19 diagnosis: serum IL-6 > 32.1 pg/mL is a severity predictor*


  • Interleukin-6 (IL-6) is a non-specific marker associated with inflammatory response and is NOT
    diagnostic of 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.
  • Results SHOULD NOT be used as a diagnostic procedure without confirmation from another medically-established diagnostic product or procedure.

Performance Characteristics

  • Sensitivity: The minimum detectable dose of human IL-6 was determined to be at 3 pg/ml.
  • Recovery: 92.63%
  • reproducibility: RSD < 10%
  • Specificity: This assay is specific to IL6 and will NOT detect other major cytokines.

Sample Information and Patient Preparation

  • Specimen Required: 2 mL serum
  • Standard Turn Around Time: 3 full days
  • Patient Preparation and Collection:
    No patient preparation needed. Collect blood sample into 1 SST tube.
  • Sample Storage:
    Store serum at -20°C until ready for shipping. Serum can be stored at refrigerated temperatures
    of 2 to 8oC for only 24 hours, after which must be frozen. Storage of serum at ambient temperature
    is NOT acceptable.
  • Test Kit contains:
    1 SST Tube
    1 Plastic transfer pipette
    1 Amber microcentrifuge tube
    1 Sample collection guide