Evaluation of C-reactive protein and serum amyloid A in the detection of inflammatory and infectious diseases in children

Background: Various biomarkers have been proposed to help diagnose inflammatory and infectious diseases. The goal of this study was to evaluate the effectiveness of some of these markers in children seen in an emergency service, and to compare a number of routinely used tests with measurements of serum amyloid A (SAA) and C-reactive protein (CRP) levels. Methods: A total of 83 children with clinically suspected inflammation (n = 17) or infection (n = 66) who had been seen at the emergency department were evaluated. Complete blood count, erythrocyte sedimentation rate (ESR), CRP (using two methods) and SAA measurements were performed. Results: There was no difference in the parameters studied between the inflammation and infectious groups. However, when the infectious group was subdivided into bacterial (n = 21) and viral infections (n = 43), significantly higher leukocyte, CRP and SAA values were observed in the former group. CRP was the most accurate indicator of inflammatory and infectious processes [Kappa concordance index (KCI) = 0.89], followed by SAA (KCI = 0.73) and ESR (KCI = 0.73). The worst results were obtained for the immature/total neutrophil ratio (KCI = 0.02). Conclusions: Measurement of CRP showed the best performance for indicating infectious or inflammatory processes. ESR and SAA had good concordance and yielded very similar results. CRP may be included in protocols for pediatric assessment in emergency departments. Clin Chem Lab Med 2010;48:493-9.