Soluble receptors to tumour necrosis factor and interleukin-6 in urine during acute pyelonephritis

We compared the urinary concentrations of soluble TNF-I (sTNF-RI), TNF-II receptors, and soluble IL-6 receptor (sIL-6R) standardized to urinary creatinine concentrations, in children with acute pyelonephritis, in children with non-renal fever and in healthy controls. These levels were related to the acute inflammatory response in the kidneys and later renal scarring, as determined by acute and 1-y follow-up with 99mTC-dimercaptosuccinic acid scintigraphy (DMSA). The concentrations of the soluble receptors were measured using enzyme immunoassay (EIA). The urinary levels of sTNF-RI were significantly higher in children with acute pyelonephritis (median 1320 pg/mmol) than in children with non-renal fever, children 6 weeks after acute pyelonephritis and healthy controls (873, 251 and 477 pg/mumol, respectively). Median sTNF-RII urine levels were also higher in acute pyelonephritis (4123 pg/mumol) than in the three control groups (2000, 964 and 1850 pg/mumol, respectively). In contrast, the highest urinary sIL-6R concentrations were found in healthy children (median 420 pg/mumol), compared to those with acute pyelonephritis (235 pg/mumol), children with non-renal fever and children 6 weeks after pyelonephritis (137 and 50 pg/mumol, respectively). No significant difference was found in any of the urinary soluble receptor levels in children with or without DMSA uptake defects at the acute or the 1-y follow-up scintigraphy. In conclusion, although the urinary soluble TNF receptor levels were higher during acute pyelonephritis, this observation was not useful for deciding which children needed follow-up after acute pyelonephritis.