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/μmol, respectively). Median sTNF‐RII urine levels were also higher in acute pyelonephritis (4123 p/μmol) than in the three control groups (2000, 964 and 1850 pg/μmol, respectively). In contrast, the highest urinary sIL‐6R concentrations were found in healthy children (median 420 pg/μmol). compared to those with acute pyelonephritis (235 pg/μmol), children with non‐renal fever and children 6 weeks after pyelonephritis (137 and 50 pg/μmol, 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.