Urinary Measurement of Neutrophil Gelatinase Associated Lipocalin and Kidney Injury Molecule-1 Helps Diagnose Acute Pyelonephritis in a Preclinical Model

Background . The study assessed whether measurement of urinary biomarkers of acute kidney injury could be helpful in diagnosing acute pyelonephritis and subsequent scarring. Method . Escherichia coli J96 (0.3 mL inoculum containing 1 × 10 9 /mL) was directly injected into the renal cortex of 3-week-old female Sprague Dawley rats ( n = 20), with saline substituted in a control group ( n = 10). Following the injection, urine was collected 2, 7, 14, 28, and 42 days after injection. Urinary neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (Kim-1), and interleukin-18 were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). The levels of the biomarkers were adjusted for creatinine. Time course changes within a group or between the groups were compared. Correlation analysis was performed to understand the relationship between urinary levels and histological scarring. Results . Significantly elevated urinary NGAL was evident at two and seven days after injection, and Kim-1 was elevated at two days after injection. Receiver operating characteristic analyses confirmed the sensitivity of these markers at these times. No urinary marker at acute stage of APN was correlated with the amount of future scarring, negating their predictive value. Conclusion . Urinary NGAL and Kim-1 could be helpful in diagnosing febrile urinary tract infection in children.