Serum Interleukin-6 and Interleukin-8 are Sensitive Markers for Early Detection of Pyelonephritis and Its Prevention to Progression to Chronic Kidney Disease

BACKGROUND: Pyelonephritis is the most common bacterial infection in children that can cause renal failure if not diagnosed or treated early. We used serum biomarker interleukins (IL-6 and IL-8) and then confirmed the results by the findings dimercaptosuccinic acid (DMSA) scan to distinguish upper-tract infection from lower-tract infection. METHODS: Serum IL-6 and IL-8 were measured in 57 children with newly diagnosed untreated urinary tract infection (UTI) documented by a positive urine culture. All children had a DMSA to determine whether serum IL6, IL-8 can be used as a marker to predict upper-tract from lower-tract infection. IL-6 and IL8 were determined by the enzyme link immunosorbent assay (ELISA) technique. RESULTS: Of the 57 patients, 24 (42%) had renal parenchymal lesions on the DMSA scan. Patients with abnormal DMSA had significantly higher serum IL-6 and IL-8 compared with those with normal DMSA scan (187.1 ± 113.1 ng/mL vs. 396.1 ± 246.0 ng/mL, P = 0.005; and 165 ± 76.1 ng/mLvs. 190.8 ± 60.8 ng/mL, P = 0.026, respectively). Pyelonephritis was more frequent in children younger than 20 months old (n = 36, 63%, P < 0.005) and more prevalent in girls (n = 36, 63%, P = 0.005). Serum IL-6 had a sensitivity of 67.3% and a specificity of 63.0% and serum IL8 had a sensitivity of 80.1% and a specificity of 73.5% in the differential diagnosis of pyelonephritis and cystitis (P = 0.03). CONCLUSIONS: Serum levels of IL-6 and IL-8 are both sensitive biomarkers of UTI and can discriminate the upper from lower tract urinary infections. Determination of these biomarkers may help to identify patients with acute pyelonephritis and need for DMSA study.