Urinary IL-8 was between 10 and 36 times higher in samples from patients with pyelonephritis37,57 and febrile UTI,44 and between 2 and 49.4 times higher in samples from patients with cystitis or a non-specific UTI (ie, a UTI not specified as upper or lower tract) than in those from healthy controls.34,49,53,60 One study, including 8 participants with cystitis found similar median urinary IL-8 in cystitis and control groups.57 This evidence concerns the gene CXCL8 and cystitis.