IL-6 may aid in early sepsis detection in children, newborns

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A new study presented at ESCMID Global 2025 highlights the potential of a faster, more reliable method for diagnosing sepsis in patients most at risk, including pregnant women, children, and newborns. Researchers found that a specific protein, interleukin-6 (IL-6), could be a strong early indicator of sepsis, outperforming traditional tests currently in widespread use.^1,2

Sepsis is a life-threatening condition caused by the body’s overwhelming response to infection. It can lead to tissue damage, organ failure, and death if not treated quickly. Globally, sepsis is estimated to cause around 11 million deaths every year. Young children—especially those under 5 years—and pregnant women are among the most vulnerable groups due to changes in their immune systems that make them more susceptible to infection. Detecting sepsis early in these groups is especially difficult, since its symptoms can resemble those of other conditions and often go unnoticed in the early stages.

The new study is the first of its kind to evaluate the diagnostic value of IL-6 across three high-risk patient populations in a real-world setting. Researchers looked at blood samples from 252 patients who were suspected of having sepsis: 111 children, 72 pregnant women, and 69 newborns. Each patient was assessed based on their type of infection—bacterial, viral, or no infection—and how their body was responding, ranging from a normal state to septic shock.

The results showed that IL-6 could reliably distinguish between bacterial and non-bacterial infections in all three groups. IL-6 had diagnostic accuracy scores, measured by AUROC (a standard test performance scale), of 0.91 in children, 0.94 in pregnant women, and 0.86 in newborns. A perfect test would score 1.0, while a score of 0.5 would be no better than chance.

In addition to identifying infections, IL-6 also helped measure how severe the sepsis was. This ability to distinguish between mild infection, full-blown sepsis, and septic shock is important because it allows health care providers to tailor treatment based on how sick the patient is.

When compared to traditional biomarkers like C-reactive protein (CRP) and procalcitonin (PCT), IL-6 showed faster and more accurate responses. According to Seán Whelan, PhD, the study’s lead author, IL-6 levels begin to rise within 1 to 2 hours after infection, peak at 6 hours, and return to normal within 24 hours. In contrast, CRP and PCT take much longer to peak—up to 48 hours in the case of CRP.

This faster response makes IL-6 especially valuable in situations where time is critical. In the study, IL-6 was able to detect bacterial infections with 91% sensitivity in children and 94% in pregnant women, meaning it correctly identified most patients who had the condition. While its sensitivity was lower in newborns (67.6%), its specificity remained high (97.1%), meaning it was still very accurate at identifying those who did not have the condition.

Researchers believe this difference in newborns may be due to the lack of a universally agreed-upon definition of neonatal sepsis and the wide range of ways it can present in that population.

Whelan noted that IL-6 is already being used in clinical settings at hospitals such as the Rotunda Hospital and Children’s Health Ireland at Temple Street. He added that the availability of IL-6 testing has improved in recent years, especially during the COVID-19 pandemic, when it was increasingly used to assess inflammation.

“Our findings reinforce the potential of IL-6 as a promising biomarker in sepsis diagnosis,” said Whelan. “With wider adoption and in combination with clinical assessment, IL-6 could significantly improve clinical decision-making and support timely, targeted treatment for high-risk patients.”

References:

1. ESCMID Global. Breakthrough study identifies promising biomarker for early sepsis detection in neonates, children, and pregnant women. Eurekalert. April 11, 2025. Accessed April 11, 2025. https://www.eurekalert.org/news-releases/1079319?

2. Whelan, S. O. et al (2025). Interleukin-6 as a diagnostic biomarker for sepsis in neonates, children and pregnant women – a real-world cohort study. ESCMID Global 2025, Vienna, Austria.