Umbilical cord blood serum procalcitonin by Time-Resolved Amplified Cryptate Emission (TRACE) technology: reference values of a potential marker of vertically transmitted neonatal sepsis

Background: Neonatal infection remains a major diagnostic problem because of non-specific clinical signs and symptoms, as well as low sensitivity and specificity of routine laboratory tests. C-reactive protein (CRP), white blood cell count, absolute neutrophil count and immature/total neutrophil ratio are the most widely used tests in the diagnosis of sepsis and provide useful information, but none of these has demonstrated to be reliable in detecting all septic infants. Procalcitonin (PCT) has been suggested as a potentially useful laboratory test performed in umbilical cord blood when perinatal bacterial sepsis is under investigation. Methods: In this study, the reference interval for umbilical cord blood serum PCT was established for the first time by Time-Resolved Amplified Cryptate Emission (TRACE) technology. Results: The reference interval for PCT in umbilical cord blood serum ranged from 0.04 to 0.43 mu g/L in 168 non-infected newborn infants (95% Cl 0.02-0.06 and 0.35-0.60 mu g/L, respectively). Cord blood serum PCT correctly classified one infected patient out of 90 newborn infants at risk of vertically transmitted sepsis and identified another neonate as a potentially infected patient despite having negative blood cultures. However, cord blood CRP misclassified 21 out of the 90 patients as infected neonates. Conclusions: Cord blood PCT measured by TRACE is a potentially more useful early marker of neonatal sepsis than cord blood CRP.