Clinical Usefulness of the Semiquantitative Procalcitonin Test in the Diagnosis of Bacterial Infections in a Third Level Children's Hospital

Background: The differential diagnosis between viral and bacterial infections can be challenging in children. Procalcitonin (PCT) has been investigated as an early marker for bacterial infections. The aim of this study was to assess the usefulness of procalcitonin (PCT) compared to C-reactive protein (CRP), white cell blood count (WBC), and absolute neutrophil count (ANC) for differentiating bacterial from viral infections in a third level pediatric hospital. Methods: Children admitted for a clinically suspected infection to the Pediatric Clinic from January 1, 2005 to December 31, 2008, who had concurrent evaluation of PCT, CRP, WCB, and ANC were included in the study. According to the diagnosis at discharge based on the ICD-9 codes, patients were classified into two groups: children with certain bacterial infections (CBI) and children with certain viral infections (CVI). PCT concentrations were determined by semiquantitative PCT-Q strips. The diagnostic performance of the markers were studied by receiver operating characteristic (ROC) analysis. Logistic regression analysis was used to evaluate the risk of bacterial infection in relation to all the study markers. Results: Among the 165 children included in the study PCT sensitivity was the same as CRP (60.56 % vs 66.19 %; p = 0.646) while PCT specificity was lower (77.27 % vs 88.18 %; p = 0.050) in the detection of bacterial infections. Conclusions: The PCT semiquantitative test is not sufficiently sensitive to be used alone as a marker of bacterial infection. (Clin. Lab. 2011;57:497-506)