Objectives: This study was performed to determine serum concentrations
of interleukin-6 (IL-6) during bacterial infections in the first week
of life and to evaluate the usefulness of IL-6 as a diagnostic test f
or perinatal bacterial infections, alone and in combination with C-rea
ctive protein (CRP). Study design: Blood was obtained from 241 newborn
children on admission to the neonatal intensive care unit and at 3 to
4 days after admission. Both samples were analyzed for IL-6, CRP, and
white blood cell count with differential. Results: Twenty-four newbor
ns were classified as having an infection. Increased serum IL-6 levels
were detected in infected compared with noninfected newborns on admis
sion (p < 0.0001). Detection of IL-6 (greater than or equal to 20 pg/m
l) alone yielded a sensitivity Of 78%, a specificity of 71%, a positiv
e predictive value of 40%, and a negative predictive value of 93%. A c
ombined parameter of IL-6 (greater than or equal to 50 pg/ml) and CRP
(greater than or equal to 10 mg/L) yielded a sensitivity of 96%, a spe
cificity of 74%, a positive predictive value of 49%, and a negative pr
edictive value of 99%. Conclusions: Used in combination with CRP, IL-6
seems to be a valuable parameter in the early diagnosis of neonatal i
nfections.