Measurement and Estimation of Glomerular Filtration Rate in Children With Neurogenic Bladder: A Prospective Study

Abstract

Objective: To evaluate the performance of different equations used to estimate glomerular filtration rate (GFR) in children with neurogenic bladder (NB).

Methods: The GFR measured with the technetium-99m-diethylenetriaminepentaacetic acid (^99mTc-DTPA) dual-plasma sample clearance method was defined as the true GFR (tGFR). The Chronic Kidney Disease in Children (CKiD) equation for serum creatinine (Scr) and/or cystatin C (Cys C) was used for GFR calculation. Estimated GFR (eGFR) using CKiD_Scr, CKiD_{Cys C}, and CKiD_{Scr+Cys C} equations was compared with tGFR in children with NB.

Results: In total, 458 children with NB were prospectively enrolled in this study. The mean tGFR was 73.84 ± 18.54 ml/min/1.73 m², mean eGFR_Scr was 77.94 ± 18.38 ml/min/1.73 m², mean eGFR_{Cys C} was 74.20 ± 17.64 ml/min/1.73 m², and mean eGFR_{Scr+Cys C} was 75.70 ± 18.07 ml/min/1.73 m². The correlation between the Scr-based equation and ^99mTc-DTPA clearance method was low (r = 0.648). The Cys C-based equations exhibited the strongest correlations: CKiD_{Cys C} (r=0.891) and CKiD_{Scr+Cys C} (r = 0.879). The overall prevalence of chronic kidney disease (CKD) was 20.7%, 19.7%, 17.5%, and 12.4% according to tGFR, eGFR_{Cys C}, eGFR_{Cys C+Scr} and eGFR_Scr, respectively. The area under the curve (AUC) for the Receiver operating characteristic (ROC) curve of the CKiD_{Cys C} equation was the highest (AUC_CKiDcys = 0.956).

Conclusion: The Cys C-based CKiD equation was the most accurate for estimating GFR compared with ^99mTc-DTPA clearance method in children with NB. The CKiD_Scr equation overestimated the GFR. The CKiD_{Cys C} equation can be used to detect initial stages of CKD in children with NB.