Dietary Therapy for Children With Congenital Solitary Functioning Kidney

Background. Renal injury, proteinuria, and hypertension, are consequences of congenital solitary functioning kidney (CSFK). Renal injury appears around 10 years of age and requires dialysis by the age of 30 years. Low protein intake attenuated renal damage in animal experimental models, uninephrectomized patients, and kidney transplant donors and recipients. Low salt intake facilitates blood pressure control. Objective. Relevant data concerning CSFK patients have not been described so far. We decided to examine long-term preventing effects of protein restriction and low-salt diet on proteinuria, kidney function, and hypertension, in this distinct polulation. Methods. Twenty-eight children with CSFK were included in a prospective observational exposure series. Following parents’ agreement, protein and salt restriction—0.85 × recommended daily allowance (RDA)—was started under dietitian supervision. Compliance verification was performed by (a) monitoring urinary urea nitrogen and body weight, (b) measuring 24-hour urine sodium. Follow-up (8-22 years, mean 15.8 years) included clinical, growth and developmental assessment, renal function, and urine protein excretion. Results. Baseline data showed normal physical assessment, arterial blood pressure kidney functions, and urinalysis. One patient had ipsilateral kidney malformation and 2 patients had systemic pathologies. Adherence to dietary restrictions: 89 ± 8% for protein and 93 ± 5% salt. At the end of follow-up, 2 patients had chronic kidney disease grade I. None had hypertension, proteinuria, or growth and development deterioration. Conclusion. Strict follow-up and controlled dietary supervision for mild protein and salt restriction prevent kidney injury proteinuria and hypertension in CSFK, without insults on growth and development.