Urine IL-8 was 3165.8 ± 4665.1 pg/mg of creatinine (mean ± SD) in the pyelonephritis group, 172 ± 350.8 pg/mg in the lower UTI group and 11.2 ± 15.1 pg/mg in the healthy control group, P < 0.001. This evidence concerns the gene CXCL8 and pyelonephritis.