Evaluation of kidney functions and related factors in children with solitary functioning kidney

Children with a Solitary Functioning Kidney (SFK) have an increased risk of developing hypertension, albuminuria and chronic kidney disease in later life. The aim of this study is to evaluate kidney function and related risk factors of pediatric patients due to single kidney function, examination of clinical features, frequency of proteinuria and hypertension in these children, It is the evaluation of patient groups classified according to their etiological causes in terms of incidence of related complications. Patients who were followed up due to the SFK in our Child Nephrology outpatient clinic were included in the study. From the medical records of patients BUN, serum creatinine, cystatin C, GFR, extended GFR and serum creatinine, cystatin C, GFR levels were evaluated at 6 months, 1 year, 3 years, 5 years. Patients were analyzed in 2 subgroups as single kidney groups that function as congenital (primary) and acquired (secondary) for etiological reasons. The patients included in our study were divided into four groups in total. The primary renal function group consisted of unilateral renal agenesis (URA) and multicystic dysplastic kidney (MKDB) patients. The only kidney group with secondary function was included non-functional single kidney (12) due to additional anomaly, and single kidney (20) patients with nephrectomy due to additional urological anomaly - trauma. 206 patients included in the study, 125 (60.7%) were boys and 81 (39.3%) were girls. The mean age of the patients was 9.36±5.27 years, and the follow-up period was 56.14±46.52 months. 20 patients GFH <60 ml/min / 1.73 m2 (11.5%), 25 patients GFH <60 ml/min / 1.73 m2 (14.4%), 32 patients (15.5%) hypertension, 22 patients (11,5%) hyperfiltration, proteinuria in 22 patients (10.7%), use of renoprotective drugs in 49 patients (23.8%), and compensatory hypertrophy in 143 patients (69.8%) and anemia in 32.5% were detected. There were 20 patients with GFR < 60 ml/min /1.73 m2, the difference between SFK groups was not significant (p=0,344, p=0,561). Renoprotective drug use and frequency of compensatory hypertrophy were higher in the secondary SFK group (p<0,05). When patients with unilateral renal agenesis and multicystic dysplastic kidney patients were not statistically different between GFR and extended GFR values (p> 0.05). Hypertension was higher in patients with renal agenesis compared to patients with multicystic dysplastic kidney (p= 0.011). Vesicoureteral reflux was observed in 33.3% of unilateral renal agenesis patients and 35.7% of multicystic dysplastic kidney patients. Ureteropelvic stenosis was detected in 16.7% of unilateral renal agenesis patients and 28.6% of multicystic dysplastic kidney patients. When unilateral renal agenesis and multicystic dysplastic kidney patients were 6 months old, 1 years, 3 years old, 5 years old, there was no statistically significant difference when creatinine, GFR and cystatin C measurements were compared (p> 0.05). In patients with renal damage, the incidence of additional urological anomaly, prematurity, UTI history, hyperuricemia, and birth weight <2500 g were found to be statistically higher than those without (p <0.05). In univariate analysis, male gender, primary SFK group, presence of additional urological anomaly, premature birth, UTI history, presence of hyperuricemia, birth weight < 2500 g were found to be associated with renal damage formation. However, in multivariate analysis, only hyperuricemia and prematurity [OR: 3,026 GA: 1,103-8,303] were associated with renal injury. When the prognosis of kidney function in the first five years of the patients included in the study was evaluated, a statistically significant decrease was observed in creatinine, cystatin c and GFR values in the 6th month, 1st year and 5th year (p< 0.001). When patients were separated according to etiological reasons and the course of renal function was reevaluated, there was no significant difference in creatinine, GFR and cystatin C values of patients with unilateral renal agenesis and multicystic dysplastic kidney (all p > 0.05). The frequency of renal injury is high in children with a solitary functioning kidney. Kidney functions of these patients start to deteriorate over the years starting from the early period. Kidney protective measures should be taken in the follow-up of these children, and high-risk patients should be identified in adulthood. Key Words: Solitary Functioning Kidney, GFR, Renal Injury, Cystatin C