Relationship between serum and urine interleukin-6 elevations and renal scarring in children with acute pyelonephritis

Objective. Acute pyelonephritis is a common infectious disease in children and can result in permanent renal damage. Interleukin-6 (IL-6) is an important mediator of inflammation in response to bacterial infection. This study investigated the potential relationship between acute-phase IL-6 and subsequent renal scarring in children with a first time febrile acute pyelonephritis. Material and methods. In total, 79 children (age range 1-120 months) with a first time febrile urinary tract infection (UTI) were included. The diagnosis of acute pyelonephritis was confirmed by 99mTc-dimercaptosuccinic acid (DMSA) renal scan. Serum and urine samples were collected for IL-6 measurement by enzyme-linked immunosorbent assay before antibiotic treatment for the infection. Results. The 79 children were divided into acute pyelonephritis (n=45) and lower UTI (n=34) groups according to the findings of DMSA scans. The initial serum and urine IL-6 levels of children with acute pyelonephritis were significantly higher compared with lower UTI (p < 0.001). Renal scarring was detected at the follow-up DMSA scans in 15 (34.1%) of the 44 children with acute pyelonephritis. Both serum and urine IL-6 levels during the acute phase of pyelonephritis were significantly higher in children with renal scarring than in those without (p=0.005 and p = 0.002). The median age of children with renal scarring was significantly lower than those without (p=0.034). Multiple regression analysis showed that higher initial serum and urine IL-6 levels and a younger age were associated with renal scarring. Conclusion. These results demonstrate that in younger children with a first time febrile acute pyelonephritis, elevations of the acute-phase serum and urine IL-6 levels were correlated with an increased risk of subsequent renal scarring.