Celiac Disease and Urinary Conditions: A Systematic Review

Background: Celiac disease (CD) is a systemic immune-mediated enteropathy with a broad spectrum of extraintestinal manifestations driven by aberrant mucosal IgA responses and increased intestinal permeability. These same mechanisms provide a compelling biological rationale for urinary tract involvement. The aim of this systematic review was to assess whether adults with CD carry an elevated risk of IgAN, UTI, or IC/BPS compared with adults without CD. Methods: A PRISMA 2020-compliant systematic review was conducted (PROSPERO: CRD420261358537). PubMed and Scopus were searched up to April 2026. Eligible studies enrolled adults (≥18 years) with confirmed CD, reported a urinary outcome, and included a comparator group. Risk of bias was assessed using the Newcastle–Ottawa Scale and Mendelian Randomization quality criteria. Results: Fifteen studies (1987–2025) were included. For IgAN (n = 13), a register-based cohort showed an over 18-fold elevated risk in adults with biopsy-confirmed CD (adj. HR: 18.98; 95%CI: 2.29–157.63), independently corroborated by Mendelian Randomization (OR: 1.44; 95%CI: 1.17–1.78). Early cross-sectional AGA studies reflect non-specific IgA dysregulation, not true CD autoimmunity. For UTI (n = 1), no significant association was identified in a single large registry study. For IC/BPS (n = 1), no clinical observational evidence exists and genetic causal analysis found no association. Conclusions: CD is consistently associated with elevated IgAN risk across independent study designs, supporting systematic CD screening in IgAN patients and prompt GFD initiation. For UTI and IC/BPS, adequately designed prospective studies are needed.