We evaluated the reliability of serum concentrations of procalcitonin for the diagnosis of early- and late-onset sepsis in a neonatal intensive care unit (NICU) setting. Timed procalcitonin determinations were prospectively obtained during two postnatal periods: 0-48 hours of age (period 1) and 3-30 days of age (period 2). In period 1, we measured procalcitonin concentrations in 83 healthy newborns (group 0) and in 120 NICU patients (14 with culture-proven sepsis, group 1A; 14 with clinical septicemia, group 1B; 75 with no evidence of infection, group 2; and 17 with uncertain findings, group 3). After we established 95% hour-specific reference ranges for group 0, we performed multiple linear regression analyses to determine which maternal, intrapartum, and neonatal complications would affect normal procalcitonin values. Maternal diabetes was the only variable identified in group 2 patients that induced a significant deviation from procalcitonin reference ranges. Analyses of the pooled procalcitonin values obtained for group 1 patients over the 48-hour period after birth yielded a sensitivity of 92.6% and a specificity of 97.5% for procalcitonin concentrations in the detection of early-onset sepsis. In period 2, blood samples from 23 cases with systemic infections were analyzed for procalcitonin concentrations at the onset of signs of infection. The control group was formed by matching four uninfected NICU patients to each infected case. None of the procalcitonin values for the 92 controls overlapped those for the cases (sensitivity and specificity, 100%). Procalcitonin is a promising marker for the diagnosis of early- and late-onset sepsis in neonates at high risk for this infection.

Background: Studies of the diagnostic accuracy of most laboratory tests for early-onset neonatal sepsis have yielded variable results. We investigated whether some of this variation might be attributable to differences in population baseline severity and risk status as well as to specific ante-and perinatal variables, independent of the presence of neonatal infection. Methods: The Score for Neonatal Acute Physiology (SNAP) was used to define illness severity, with SNAP Perinatal Extension (SNAP-PE) used to define the combined physiologic and perinatal mortality risk. A total of 134 ill newborns (19 with early-onset infection and 115 with no infection) were available for simultaneous analysis of the association of SNAP, SNAP-PE, and maternal and perinatal variables with C-reactive protein (CRP), interleukin-6 (IL-6), and procalcitonin (PCT) concentrations at birth and at 24 and 48 h of life. Results: Early-onset neonatal infection was associated with significant increases in CRP, IL-6, and PCT concentrations at all three time points, independent of illness severity. However, among babies without infection, higher SNAP and SNAP-PE scores were associated with higher IL-6 concentrations at birth. Certain maternal or perinatal variables altered IL-6 and PCT values in the infected as well as in the uninfected neonates. However, if different cutoff points were used at any of

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There are differences in the serum concentrations of IL-6 that can be helpful in detecting early and late onset infection in preterm and term neonates. During the first 48 h of life serial IL-6 determinations are necessary so as not to overdiagnose infection in a neonatal intensive care setting.