Follow up of renal outcomes in children with solitary kidney

Background: Solitary kidney (SK) affects 1/1000 people worldwide, and there are controversies concerning renal outcomes in these patients. This study aimed to investigate clinical findings and renal outcomes in children with SK and to compare the results for congenital (CSK) and acquired SK (ASK) groups.Methods: The study included patients that presented to our pediatric nephrology department with SK between January 2010 and January 2021. Demographic and clinical data were recorded retrospectively.Results: Of the 101 patients with SK, 71 had CSK (55 had unilateral renal agenesis and 16 had a multicystic dysplastic kidney) and 30 had ASK (17 had previously undergone unilateral nephrectomy due to a renal tumor and 13 had urological structural anomalies). There were nine patients (9%) with renal injury. The serum uric acid level was significantly higher and the estimated glomerular filtration rate was significantly lower in the patients with ASK compared with those with CSK (p = 0.005 and p < 0.001, respectively). There was a positive correlation between renal injury and the uric acid level (p < 0.001, r = 0.45).Conclusion: In addition to the management of blood pressure and proteinuria, it is important to control uric acid levels in patients with SK, especially those with ASK, to prevent renal injury. The ASK group has a greater risk of renal injury than the CSK group. There is a need for new markers to predict early stage renal damage in SK.