Can urinary albumin-creatinine ratio be used as a surrogate for protein-creatinine ratio in the diagnosis and management of pediatric steroid sensitive nephrotic syndrome?

backgroundIn pediatric nephrotic syndrome (NS), conventionally, spot urinary protein-creatinine ratio (PCR) is used for diagnosis and to define relapse and remission. This study evaluates whether urine albumin-creatinine ratio (ACR) can reliably predict proteinuria status to manage NS according to existing guidelines, when PCR values are unavailable.

methodsChildren between 1 to 18 years of age with steroid sensitive NS (SSNS) were included. Blood samples for albumin, creatinine, and first or second morning urine samples for albumin, total protein, and creatinine were collected; PCR and ACR were calculated in mg/mg. Correlation between ACR and PCR was assessed using Spearman's rank correlation coefficient and agreement by Bland-Altman analysis. ACR thresholds corresponding to PCR-defined remission and relapse were derived using fivefold internal cross-validation with bootstrap resampling and linear regression modelling. Diagnostic performance was evaluated by sensitivity and specificity using PCR thresholds as the reference standard.

resultsIn 202 patients (median age 7.4 years, 63% male, normal creatinine for age), ACR and PCR were highly correlated (r

conclusionsIn this study, spot urinary ACR had very strong association and good agreement with PCR in children with SSNS. The ACR cutoffs obtained can be useful in diagnosis and follow-up of SSNS or in evaluating retrospective study data when ACR is available rather than PCR.