This multicenter observational cross-sectional study aims to evaluate the prevalence of chronic kidney disease (CKD) in pediatric patients with inflammatory bowel disease (IBD) and to compare it with a control group without IBD.

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, are chronic conditions that can also affect organs outside the intestine. Among these, kidney involvement has been reported, but data in pediatric populations are limited.

The study will collect clinical, laboratory, and demographic data from pediatric patients with IBD and matched controls without IBD. The main objective is to estimate the prevalence of CKD in children with IBD and compare it with that observed in the control group. Secondary objectives include describing patient characteristics and exploring potential associations between CKD, disease activity, and medical therapies.

The results of this study may improve the understanding of kidney complications in pediatric IBD and support earlier diagnosis and better clinical management.

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic relapsing conditions that frequently begin during childhood or adolescence. In pediatric patients, IBD often presents with more severe disease phenotypes and may be associated with extraintestinal manifestations involving multiple organ systems.

Renal involvement is among the reported extraintestinal manifestations of IBD and includes a wide spectrum of conditions, such as nephrolithiasis, tubulointerstitial nephritis, glomerulonephritis, and chronic kidney disease (CKD). While these complications are relatively well described in adult populations, epidemiological data in pediatric patients remain limited, particularly in the Italian setting.

Understanding the prevalence of CKD and its potential associations with disease activity and medical therapy is essential to improve early detection and long-term outcomes in pediatric patients with IBD.

Inclusion Criteria:

• Pediatric patients aged between 2 and 17 years
• For the case group: confirmed diagnosis of inflammatory bowel disease according to Porto criteria
• For the control group: absence of current or previous diagnosis of inflammatory bowel disease
• Availability of clinical and laboratory data required for study evaluation
• Written informed consent from parent or legal guardian, and assent from the minor when applicable

Exclusion Criteria:

• History of pre-existing renal disease (congenital or acquired before IBD diagnosis)
• Presence of conditions that may affect renal function (e.g., diabetes mellitus, hypertension, chronic use of nephrotoxic drugs)
• Lack of informed consent

Pediatric patients aged 2 to 17 years recruited from participating centers, including patients with inflammatory bowel disease and a matched control group without IBD.