OBJECTIVE: Upper urinary tract infection (UTI) is the most common serious bacterial infection in childhood. Patients with upper UTI have a risk for renal scarring with subsequent complications including hypertension, proteinuria, and progressive renal failure. However, the predictive biomarkers of renal scarring in children with upper urinary tract infection are still unknown. In this study, we evaluated whether soluble ST2 levels can be biomarkers of subsequent renal scarring in patients with upper UTI. 
METHOD: All subjects were enrolled in Yamaguchi University Hospital between 2008 and 2016. We retrospectively studied pediatric patients with upper UTI. Twenty-eight children had an upper UTI with (n=14) and without (n=14) renal scarring and underwent 99mtechnetium dimercaptosuccinic acid imaging. In addition, 13 control subjects were enrolled. The clinical data and serum cytokine levels, including soluble ST2 levels, were compared between those with and without renal scars using the Mann-Whitney U-test and Chi-square test as statistical analysis. 
RESULT: Serum soluble ST2 levels were significantly higher in the scar group than in the non-scar group, whereas there were no differences in the levels of serum interferon-?, interleukin-6, interleukin-10, soluble tumor necrosis factor receptor 1, and transforming growth factor-? between the scar and non-scar groups. The area under the curve for differentiating between the non-scar and scar groups on the basis of measurements of serum soluble ST2 was 0.79, with a sensitivity and specificity of 92.9% and 64.3%, respectively.
CONCLUSION: These results suggest that serum soluble ST2 levels on admission could be a useful biomarker of subsequent renal scarring in pediatric patients with upper UTI.