WBC (p = 0.001), neutrophils (p < 0.001), lymphocytes (p < 0.001), RBC (p < 0.001), hemoglobin (p < 0.001), CRP (p < 0.001), PCT (p < 0.001), and IL-6 (p < 0.001) were significantly different between the hydronephrosis group and the pyonephrosis group in the single factor analysis of blood cell analysis and infection. Here, IL6 is linked to infection.