Elecsys® IL-6

Early marker in acute inflammation

Elecsys IL-6

Diagnosis of sepsis - Time matters

Clinical signs suggestive of sepsis are non-specific, making diagnosis of sepsis difficult.5 Blood cultures remain the gold standard for diagnosis of patients with suspected sepsis, however, they have several limitations.6, 7


Limitations of blood cultures in sepsis diagnosis:6, 7

  • Require up to 5 days to obtain the results
  • Lack sensitivity
  • Easy to contaminate
  • Cannot assist on early sepsis management decisions


Timely diagnosis and initiation of effective antibiotic treatment and sepsis management has been shown to improve patient outcomes. Almost 80% of patients with severe sepsis survive if treatment is initiated within 1 hour of diagnosis. Survival declines rapidly if treatment is delayed further, dropping to only 42% if initiated 6 hours after diagnosis.8 In addition, it is desirable to prevent unnecessary antibiotic usage in order to reduce treatment costs, reduce the risk of adverse reactions and to slow down the spread of antibiotic-resistant bacteria.9, 10

See figure

Biomarkers in sepsis

There is considerable unmet medical need in sepsis, and biomarkers may have an important clinical role to play. Biomarkers can indicate the presence of sepsis, differentiate bacterial from viral or fungal infection, differentiate local from systemic infection, stratify severity of sepsis, may help to guide antibiotic therapy, provide prognostic information, evaluate response to therapy, predict septic complications and predict the development of organ dysfunction. However, the exact role of biomarkers is yet to be defined.5

Unmet medical needs in the management of sepsis and suspected sepsis:

  • Diagnosis and differential diagnosis of infection5
  • Recognition and stratification of severity of sepsis5
  • Early and appropriate decision regarding antibiotic therapy decisions9, 11


Interleukin-6 (IL-6) is an early marker for inflammation in sepsis


Il-6, a key mediator for inflammation and an early alarm signal of infection that becomes elevated as part of the inflammatory response, has emerged as a valuable biomarker in the management of sepsis.12


IL-6 levels predict development of septic complications


In a study of 1,032 patients with severe trauma, patients who subsequently developed septic complications had the highest IL-6 levels on day 1 following injury.14 Similarly, in a study of 50 patients following major surgery, IL-6 levels were correlated with the development of septic complications during the first 5 days following surgery (area under the curve [AUC] 0.82; 95% CI: 0.66 – 0.98), with a sensitivity of 90% and a selectivity of 58%. Furthermore, when IL-6 levels and clinical indicators were combined, sensitivity and selectivity increased to 100% and 79%, respectively.15

See figure

IL-6 levels predict severity of sepsis

Early peak IL-6 levels correlate significantly with the development of SIRS and sepsis. The degree of elevation inIL-6 levels can be used to differentiate SIRS from severe sepsis anf septic shock, with higher IL-6 levels correlating with increased severity.16 

See figure

IL-6 levels are associated with patient outcome and organ dysfunction

As a marker for systemic inflammation, high IL-6 levels may be predictive of future organ dysfunction.12 In addition, continually elevated IL-6 levels have been reported to be predictive of mortality in patients with sepsis. 16




  • Aid in the management of critically ill patients
  • Optimized laboratory workflow
  • Available on a fully automated platform
  • Small sample volume
Elecsys IL-6

Elecsys® IL-6

  • Assay time

    18 minutes

  • Sample material

    Serum, Li-heparin and K2- and K3-EDTA plasma

  • Sample volume

    30 µL

  • Measuring range

    1.5 – 5,000 pg/mL

  • Analytical sensitivity

    1.5 pg/mL

  • Functional sensitivity

    5 pg/mL

  • Traceability

    WHO Standard NIBSC 1st IS 89/548



  1. Pierrakos, C., & Vincent, J. (2010). Sepsis biomarkers: a review. Crit Care, 14(R15).
  2. Dark, P., Wilson, C., Blackwood, B., McAuley, D., Perkins, G., et al. (2012). Accuracy of LightCycler SeptiFast for the detection and identification of pathogens in the blood of patients with suspected sepsis: a systematic review protocol. BMJ Open, e000392.
  3.  Schuetz, P., Christ-Crain, M. & Mueller, B. (2008). Procalcitonin and other biomarkers for the assessment of disease severity and guidance of treatment in bacterial infections. Adv Sepsis, 6(3), 82-89.
  4. Kumar, A., Roberts, D., Wood, K., Light, B., Parrillo, J., et al. (2006). Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in hu septic shock. Crit Care Med, 34(6), 1589-1596.
  5. Nobre, V., Harbarth, S., Graf, J., Rohner, P. & Pugin, J. (2008). Use of procalcitonin to shorten antibiotic treatment duration in septic patients. Am J Respir Crit Care Med, 177, 498-505.
  6. Schuetz, P., Briel, M., Christ-Crain, M., Stolz, D., Bouadma, L., et al. (2012). Procalcitonin to guide initiation and duration of antibiotic treatment in acute respiratory infections: an individual patient data meta-analysis. Clin Infect Dis, 55(5), 651-662.
  7. Silva, E., de Almeida Pedro, M., Beltrami Sogayar, A., Mohovic, T., de Oliveira Silva, C., et al. (2004). Brazilian Sepsis Epidemiological Study (BASES study). Crit Care, 8(4), R251-260.
  8. Schuetz, P., Albrich, W. & Mueller, B. (2011). Procalcitonin for diagnosis of infection and guide to antibiotic decisions: past, present and future. BMC Med, 9(107).
  9. Ventetuolo, C., & Levy, M. (2008). Biomarkers: Diagnosis and risk assessment in sepsis. Clin Chest Med, 29, 591-603.