Rapid changes in serum IL-6 levels in preterm newborns with Gram-negative early-onset sepsis

•Early-onset sepsis (EOS) is an important cause of morbidity and mortality.•This retrospective case review focuses on 6 preterm newborns with EOS.•Serum interleukin-6 (IL-6) levels markedly change during first 72 hrs of life.•The changing pattern of IL-6 clearly differs between survivors and mortality cases.•Serial serum IL-6 determinations may be useful for monitoring sepsis severity. Early-onset sepsis (EOS) remains a leading cause of morbidity and mortality for newborns, especially in preterm birth. Serum IL-6 levels are used as an accurate marker for EOS; however, no study has focused on the changes in serum IL-6 levels in newborns with EOS. Here, we investigated 6 preterm newborns (23.4–28.2 wks’ gestational age) with birthweights of 570–1080 g who were diagnosed with EOS. All newborns received active treatment, including exchange transfusions and/or polymyxin B-immobilized fiber column direct hemoperfusion for septic shock. In the 3 surviving newborns, serum-IL-6 levels peaked at >500,000, 256,500, and 356,000 pg/mL within 12 h of life, and then decreased to 500,000, 198,000, and 1,354,000 pg/mL, respectively, prior to death. Therefore, in preterm newborns suspected of EOS, serial serum IL-6 determinations would be useful for not only detecting EOS, but also for monitoring sepsis severity.