Early Diagnosis of Solitary Functioning Kidney: Comparing the Prognosis of Renal Agenesis and Multicystic Dysplastic Kidney

Abstract Background Individuals with congenital solitary functioning kidney (SFK) are at an increased risk of kidney damage. According to some studies, the risk is higher in unilateral renal agenesis (URA) than in unilateral multicystic dysplastic kidney (UMCDK). We hypothesized that with early detection of children with URA and UMCDK, there would be no difference in the presence of hypertension, proteinuria, and reduced glomerular filtration rate (GFR) between URA and UMCDK. Methods Based on a long-term follow-up protocol, we evaluated a cohort of 160 children followed from birth for SFK (84 with URA and 76 with UMCDK) detected by prenatal or routine neonatal ultrasound screening. Hypertension, proteinuria and elevated GFR were monitored as markers of kidney damage. We compared the characteristics and outcomes of the subgroups of children with URA and UMCDK. Results GFR was reduced in 42 (26.2%) children, of whom 41 showed only mild reduction. Hypertension and proteinuria were found in 22 (13.8%) and 14 (8.8%) children, respectively. Combined kidney damage was present in 57 (35.6%) children. The UMCDK and URA subgroups differed in GFR at final examination, with UMCDK patients being significantly more likely to have normal GFR compared to URA patients (82% vs 67%; p = 0.039). Conclusions One third of the children showed signs of SFK damage, albeit mild. Patients with URA had reduced GFR significantly more often than those with UMCDK, but did not differ in the rates of hyperfiltration injury or congenital anomalies of the kidneys and urinary tract (CAKUT) in SFK.