CALCA and acute pyelonephritis: However, interestingly, the second European validation we performed demonstrated that, in children with a proven acute pyelonephritis, PCT is significantly higher in children with high-grade VUR (≥3) than in those with low-grade or no VUR (1.5 ng/mL, interquartile range: 0.5–4.0 versus median 4.0 ng/mL, inter-quartile range: 1.5–7.0, resp.; P < .001).