645 SONOGRAPHIC ASSESSMENT OF THE EFFECT OF VESICOURETERAL REFLUX AND URINARY TRACT INFECTIONS ON GROWTH OF THE PEDIATRIC SOLITARY KIDNEY

Abstract

INTRODUCTION AND OBJECTIVES: Many papers have addressed the effect of vesicoureteral reflux (VUR) and urinary tract infections (UTIs) on renal growth. Studies have shown that patients with solitary kidneys, especially those with congenital anomalies of the kidneys and urinary tract are more likely to end up with chronic kidney disease and end stage renal disease. Based on sonographically determined renal length we evaluated the effect of VUR and UTIs on the growth of solitary kidneys. METHODS: We retrospectively reviewed a cohort of 158 patients with the diagnosis of solitary or functionally solitary kidney seen in a pediatric urology practice between 2001 and 2011. Patients between 1 month and 18 years old with at least one ultrasound renal length measurements were included in the study. A total of 751 ultrasounds were included from 42 patients with VUR and 116 without VUR. Based on a linear mixed effects model, we investigated the influence of VUR and UTIs on the renal growth rate for solitary kidneys. Interactive effects between age, VUR and UTI status were also modeled. RESULTS: The VUR subgroup had more ultrasounds on average (p 0.001). The left solitary kidney tended to be larger than the right (p 0.042). Kids with VUR did not have a statistically significant larger number of UTIs (p 0.25). Solitary kidneys started out the same size regardless of VUR status but started to cross as patients aged. A solitary kidney with neither VUR nor UTIs grew 0.49 cm per year, while a solitary kidney with VUR grew 0.40 cm per year (p 0.001) and a solitary kidney with VUR and UTIs grew 0.31 cm per year (p 0.005). CONCLUSIONS: Our analysis shows that solitary kidneys start equal in size but that VUR and UTIs independently cause a statistically significant slower growth rate. The kidneys become relatively smaller over time as compared to those without VUR and UTIs. This suggests that the effect of VUR and UTIs on the growth of the solitary kidneys persists throughout childhood. Further studies are needed to evaluate the mechanism of this effect, whether these patients eventually develop renal insufficiency and whether more aggressive early management would be warranted.