IgE-mediated food allergy and upper urinary tract disorders in children: A matched study.

BACKGROUND: Food allergy involves type 2 immune activation and epithelial-barrier dysfunction beyond the gut and airway. Whether IgE-mediated food allergy is associated with upper urinary tract disorders in children, and whether any association is anatomically specific is unknown. METHODS: In a frequency-matched cross-sectional study using Israeli health-maintenance organization records (2001-2025), 879 children (<16 years) with allergist-confirmed IgE-mediated food allergy were matched 1:4 to 3516 controls on age, sex, population sector, socioeconomic status, and body mass index. The primary outcome was a composite of upper urinary tract disorders (vesicoureteral reflux [VUR], hydronephrosis, or acute pyelonephritis); lower urinary tract and genital conditions served as negative controls. Odds ratios were estimated by logistic regression, adjusted for atopic dermatitis and asthma. RESULTS: The upper-tract composite was more prevalent with food allergy (4.0% vs. 1.1%; OR 3.9, 95% CI 2.4-6.2). VUR (OR 12.1), hydronephrosis (OR 2.6), and acute pyelonephritis (OR 9.4) were each increased; lower urinary tract (OR 1.2) and genital conditions were not. Urology visit rates were similar between groups. After adjustment for atopic dermatitis and asthma, VUR (adjusted OR 9.2, 95% CI 4.5-16.5) and the composite (aOR 2.1) remained elevated, whereas hydronephrosis and pyelonephritis attenuated. Early-life antibiotic exposure was only modestly higher (aOR 1.2). CONCLUSION: IgE-mediated food allergy was associated with upper, but not lower, urinary tract disorders; the VUR association was independent of atopic comorbidity. Because these anomalies are congenital, the pattern likely reflects shared susceptibility rather than causation, warranting prospective study.