Procalcitonin, recognized as a possible biomarker for sepsis and severe inflammation, has been proposed to distinguish acute pyelonephritis from cystitis35 and urinary neutrophil gelatinase-associated lipocalin to separate UTI from other febrile infections and to predict acute pyelonephritis36–38 and renal scarring.15,39 These parameters were not identified as markers of acute disease severity in this study. The gene discussed is LCN2; the disease is acute pyelonephritis.