CALCA and bacterial infectious disease: Further supporting its diagnostic utility, Martinez-Albarran et al. (2009) [9] demonstrated PCT’s superior specificity (80.5% at 0.67 ng/mL) over CRP (72.2% at 9.06 mg/dL) for bacterial infection confirmation in 54 pediatric febrile neutropenia episodes, with both markers significantly differentiating high- and low-risk groups (PCT: p = 0.003; CRP: p = 0.001).