RESUMEN
Procalcitonin has been recently advocated as a marker of bacterial infection. Because of its shorter half-life and earlier ascent it offers advantages over C-reactive protein [CRP] This study aims to evaluate diagnostic markers of infection, comparing procalcitonin with more conventionally used markers of infection as C-reactive protein and leucocyte count in critically ill children admitted to hospital. A prospective observational study was performed during which plasma procalcitonin, serum C reactive protein, and leucocyte count were measured in 58 infants and children [mean age 23.6 months] on admission to hospital Patients were classified as follows: 12 patients with generalized bacterial infection and septic shock, 13 patients with viral infection; 13 patients with localized bacterial infection; and 20 non-infected controls. Optimum sensitivity, specificity, predictive values, and area under the receiver operating characteristic [ROC] curve were evaluated. Admission procalcitonin was significantly higher in children with generalized bacterial sepsis [median 115.2; range 98.4-224.07ng/ml], compared with localized bacterial infection [77.45; 54.5-112.7ng/ml], viral infection [35.6; 17.9-57.2 ng/ml], and controls [2.07; 0-5.01 ng/ml]. Comparing systemic bacterial infection with other groups of patients, area under the ROC curve was 0.984 for procalcitonin [95% CI; 0.878-0.993], 0.856 for C reactive protein [95% CI; 0.704-0.948], and 0.878 for leucocyte count [95% CI; 0.731-0.961]. Cut off concentrations of procalcitonin for optimum prediction generalized bacterial sepsis were > 96.6 ng/ml and C reactive protein > 24 mg/dl. A procalcitonin concentration > 57.0 ng/ml identified all patients with bacterial infection or generalized bacterial sepsis. Plasma procalcitonin concentration is a better diagnostic marker of bacterial infection than C reactive protein or leucocyte count in critically ill children. A procalcitonin concentration of >96.6 ng/ml might be useful in differentiating severe bacterial disease in infants and children