The First Report on the Frequency of Asymptomatic Proteinuria in Iranian School-aged Children

Abstract

Background: Proteinuria is a well-known indicator of renal dysfunction. In this study, we evaluated the frequency of proteinuria in a sample of healthy Iranian elementary school students using both dipsticks and urine albumin-to-creatinine ratio (UACR) methods. Materials and Methods: This cross-sectional study was performed on 478 school students aged 7-9 years who were selected by multistage random cluster sampling from Isfahan city, Iran. A clean midstream first-morning urine sample was obtained from each subject. Urine samples were examined by dipstick method, and accordingly, they were reported as negative; trace; 1+; 2+; 3+; and 4+. UACR was determined in samples with positive dipstick proteinuria (defined as trace or greater). Results: This study included 478 students (42.8 boys), with mean age of 7.0 +/- 0.4 years. Positive dipstick was detected in 124 (25.9) cases. The frequency of positive dipstick proteinuria was significantly higher in the girls than boys (29.6 vs. 20.9, respectively; P = 0.04). In cases with a positive dipstick, 10 (2.1) cases had UACR 30-300 mg/g. The frequency of UACR of 30-300 mg/g was 1.4 and 2.5 in boys and girls, respectively. There was no significant difference in the frequency of UACR 30-300 mg/g in terms of gender (P = 0.4). None of the subjects had UACR above 300 mg/g. Conclusion: While the frequency of asymptomatic proteinuria varies widely across different studies, we found a higher rate of proteinuria in Iranian children. Cost-effectiveness analyses are needed to justify large screening program for detecting asymptomatic proteinuria, as a cardinal manifestation of kidney disease, in Iranian children.