Impact of sepsis on the urinary level of interleukin-18 and cystatin C in critically ill neonates

Urinary interleukin-18 (uIL-18) and cystatin C (uCysC) are biomarkers of acute kidney injury (AKI). We hypothesized that in non-AKI neonates, the level of uIL-18 and uCysC would be higher in those with sepsis compared to those without sepsis. The aims of this study were to determine the association between urinary biomarkers and sepsis in non-AKI critically ill neonates, and to evaluate whether uIL-18 and uCysC could serve as predictors of sepsis in this population. The study included 111 non-AKI critically ill neonates with acute clinical deterioration suggestive of sepsis: 26 with infection, 57 without infection, and 28 were assigned to the unclassified group. Urinary samples were collected and a full sepsis screen was performed at the time of enrollment. The level of uIL-18, but not uCysC, was significantly elevated in non-AKI septic neonates. Urinary IL-18 was an independent factor associated with sepsis assessed by multivariate analysis, had odds ratio of 1.73 (95 % CI 1.15 to 2.58, p = 0.008), and achieved the area under the receiver operating characteristic curve of 0.74 for predicting the presence of sepsis in non-AKI critically ill neonates. Sepsis has an impact on the level of uIL-18, but not on the uCysC in non-AKI neonates, suggesting systemic infection might influence the diagnostic value of uIL-18 to detect AKI in the general population.