Clinical studies further identified cytokines such as IL-6 and IL-8 as activated in this patient group.9–12 While systemic host response parameters like leucocyte counts and C-reactive protein (CRP) levels are widely used diagnostically and leukocyturia is indicative of UTI,13–15 there are at present no innate immune response parameters that can accurately grade acute disease severity or identify the subset of patients, who develop acute pyelonephritis or renal scarring.16 Here, CRP is linked to acute pyelonephritis.