Abstract
Introduction: Nephrotic syndrome in children is characterized by substantial proteinuria, yet 24‑hour urine collection remains difficult to perform reliably in pediatric practice. The spot urine protein‑to‑creatinine ratio (UP/CrR) offers a more feasible alternative for estimating daily protein loss.
Objectives: This study evaluated the accuracy and predictive performance of this surrogate measure compared with 24‑hour urine protein excretion in children with nephrotic syndrome.
Materials and Methods: This cross‑sectional study was conducted on 100 children aged 3–14 years who attended two pediatric clinics in Yazd between June and December 2025. Participants with nephrotic syndrome who provided informed written consent and had complete demographic and laboratory data, including spot UP/CrR and 24‑hour urine protein excretion, were included. The primary measurement outcome was assessing the correlation between the spot UP/CrR and 24‑hour urine protein excretion.
Results: The study included 100 pediatric patients with nephrotic syndrome, with a mean age of 8.82 ± 3.29 years. A significantly strong positive correlation was observed between the UP/CrR and 24‑hour urine protein excretion across the whole cohort (r = 0.772) and within sex‑specific subgroups. Linear regression analyses further confirmed this association in both unadjusted and adjusted models. For all participants, each unit increase in the UP/CrR was associated with a proportional 2.89 mg rise in 24‑hour urine protein excretion, an effect that remained stable after adjusting for age, body mass index (BMI), and gender (B = 2.94).
Conclusion: These findings demonstrate that the UP/CrR is a strong and reliable predictor of 24‑hour urine protein excretion in children with nephrotic syndrome, and the use of the spot UP/CrR as a practical, cost-effective, and accessible surrogate for quantifying daily proteinuria in clinical settings is suggested.