CALCA and bacterial urinary tract infection: Another study identified that serum PCT and C-reactive protein (CRP) could be utilized as biomarkers for differentiating upper UTI and lower UTI in children, while the sensitivity (90.47%) and specificity (88.0%) of PCT were better than that of CRP (sensitivity was 85.7%, specificity was 48%), revealing that PCT is a more suitable biomarker for differential diagnosis in children [17].