Interleukin – 6 (IL-6)

Interleukin-6 (IL-6) is a pleiotropic cytokine with a wide range of functions including induction of the acute phase response and regulation of innate and adaptive immunity. IL-6 production is rapidly induced in the course of acute inflammatory reactions associated with injury, trauma, stress, infection, brain death and neoplasia

IL-6 concentrations in trauma patients may predict later complications from additional surgical stress or indicate missed injuries or complications. Sequential measurements of IL-6 in patients admitted to the intensive care unit (ICU) can be useful in evaluating the severity of systemic inflammatory response syndrome (SIRS), sepsis and septic shock and as a prognostic marker. IL-6 is also useful as an early marker for the detection of neonatal sepsis. In addition, IL-6 plays a role in chronic inflammation e.g. rheumatoid arthritis.

In patients with COVID-19 due to SARS CoV-2 infection, increased concentrations of IL-6 have been shown to correlate with severity of disease, risk of respiratory failure and development of SIRS though specific cut-offs have not yet been established.

<7 pg/mL

Reference range derived from kit manufacturer; 95^th centile of apparently healthy individuals (n=817).

Measurements performed on samples from 281 ICU patients with either a known or suspected infection. The patients were classified into categories based on the ACCP/SCCM (American College of Chest Physicians / Society of Critical Care Medicine) consensus criteria: SIRS, sepsis, severe sepsis and septic shock. The median IL‑6 values of the patients with SIRS (n = 94) or sepsis (n = 65), severe sepsis (n = 60) or septic shock (n = 62) were as follows:

Roche Elecsys method (cobas e411).

Falsely low results may be obtained for this test due to biotin interference. Samples should not be taken from patients receiving therapy with high biotin doses (>5 mg/day) until at least 8 hours (ideally 2 days) following the last biotin administration.