Assessing the Accuracy of Diagnostic Tests to Quantify Proteinuria in Nephrotic Children: A Cross-Sectional Study

Abstract

Objective: To assess the diagnostic accuracy of 24-hour proteinuria estimation and urine dipstick-taking spot urine protein
creatinine ratio as the gold standard in children with steroid-sensitive nephrotic syndrome.

Study Design: Cross-sectional analytical study.

Place and Duration of Study: Department of Paediatric Nephrology, Sindh Institute of Urology and Transplantation, Karachi Pakistan, from Oct 2020 to Mar 2021.

Methodology: Proteinuric children were enrolled to quantify proteinuria by 24-hour urine protein estimation, spot urine
protein creatinine ratio and urine dipstick. Sensitivity analysis was performed, and receiver operating curves were plotted to
assess the diagnostic accuracies of 24-hour proteinuria and urine dipstick against spot urinary protein creatinine ratio. Scatter plots compared the correlation of serum albumin and cholesterol with 24-hour urine protein estimation and spot urine protein creatinine ratio.

Results: Forty-two children with a median age of 8 years (IQR 6–10) were included. Nephrotic range proteinuria was detected in 39(93%) children with spot ratio, 16(38%) cases using 24-hour proteinuria estimation and 50% with a urine dipstick.Twenty-four-hour protein estimation showed a sensitivity of 63.4%, and urine dipstick had a sensitivity of 53.8% in detecting nephrotic range proteinuria compared to spot ratio with a negative predictive value of 6.3% and 14.3%, respectively.Hypoalbuminemia and cholesterol correlated better with spot ratio than 24-hour proteinuria with r- values 0.0143 and 0.0713, respectively.

Conclusion: Twenty-four-hour urine protein estimation and dipstick correlate with spot urine protein creatinine ratio in
detecting nephrotic proteinuria with no statistical difference in diagnostic accuracy.