Renal functional reserve in children with apparently normal congenital solitary functioning kidney

ObjectiveThe aim of the study was to investigate renal functional reserve (RFR) and to assess its relationship with serum cystatin C and blood pressure in children with apparently normal congenital solitary functioning kidney (SFK).Material and methodsRFR was obtained from the difference of endogenous creatinine clearance (CrCs) before and after a meat-free oral protein load (OPL) in the patients who were pre-treated with cimetidine. Serum cystatin C and urinary protein excretion were determined before and after OPL.ResultsAmong 22 patients (13 boys), aged 9.5 ± 4.3 years, 72.7% had increased serum cystatin C, and 54.5% had decreased RFR. Following OPL, CrCs and urine creatinine increased, while serum creatinine and cystatin C remained unchanged. The multiple regression analysis demonstrated that cystatin C could predict more than 90% of RFR variability.ConclusionHalf of the patients with apparently normal SFK had decreased RFR. Serum cystatin C is one of the best predictors of RFR.

► Renal functional reserve (RFR) was investigated in children with solitary kidney.
► Majority had renal dysfunction when estimated by serum cystatin C and RFR.
► Solitary kidney function should be tested by RFR and cystatin C.