CALCA and acute pyelonephritis: In a smaller group of children (n = 54), Grevaix et al also confirmed a higher level of PCT in the setting of parenchymal damage compared with lower UTI.20 In another prospective study of 64 children, Smolkin et al demonstrated that in acute pyelonephritis, the median PCT was 3.41 μg/L (range 0.36 to 12.4) while in lower UTI, the median PCT was 0.13 μg/L (range 0.02 to 2.15), P < 0.0001.21 In this study, using a cut-off of 0.5 μg/L, PCT had a sensitivity of 94.1% and specificity of 89.7% for detecting pyelonephritis.