[Procalcitonin a marker in the diagnostic of the newborn with systemic infection].

Background: Laboratory test used in the diagnosis of neonatal sepsis have a low specificity. Recently, procalcitonin has been proposed as a marker to identify the presence of systemic infections. The objective of the study was to evaluate the sensibility and specificity of procalcitonin as a marker of systemic infection in newborn with a suspicion of neonatal sepsis using a blood culture as a gold standard.
Methods: 21 newborn with a suspicion of neonatal sepsis were included in the study, postnatal age 8.3 +/- 5.2 days in a period from October 2003 to a January 2004. Procalcitonin, were measured at the moment of clinical diagnosis and after 24 and 48 hours and twice blood culture were done.
Results: Seven blood cultures were positive at the moment of diagnosis as well as 21 determinations of procalcitonin, sensibility 85.7%, specificity 21.7%; (OR = 1.63, 95% CI = 0.14-19.4); determinations after 24 hours showed procalcitonin sensibility and specificity of 85.7% and 28.5% (OR = 2.4, 95% CI = 0.22-26.6) and after 48 hours 100% of sensibility and 42.8% of specificity (OR = 1.75, 95% CI = 1.11-2.75]).
Conclusions: Positive procalcitonin has a good sensibility and moderate specificity 48 hours after clinical diagnosis of neonatal sepsis.