Renal Dysfunction in Patients With Inflammatory Bowel Disease and the General Population (NEPHRO-IBD)

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic inflammatory disorders of the gastrointestinal tract that are frequently associated with extraintestinal manifestations. These manifestations may involve multiple organ systems, including the musculoskeletal, dermatologic, hepatobiliary, ocular, and renal systems. While several extraintestinal manifestations of IBD have been well described, renal complications remain relatively underrecognized and insufficiently investigated. Renal manifestations associated with IBD may include nephrolithiasis, amyloidosis, tubulointerstitial nephritis, glomerulonephritis, urinary tract fistulas, and urothelial malignancies. In addition to disease-related mechanisms, potential contributing factors include immune dysregulation, genetic susceptibility, environmental factors, and nephrotoxic effects of medications used in the treatment of IBD, such as 5-aminosalicylates or thiopurines. Previous studies suggest that patients with IBD may have an increased risk of chronic kidney disease (CKD) and acute kidney injury (AKI). However, the true prevalence and determinants of renal dysfunction in patients with IBD remain unclear due to limited prospective data. The NEPHRO-IBD study is a multicenter prospective observational study designed to evaluate the prevalence of renal dysfunction and renal complications in adult patients with inflammatory bowel disease compared with individuals from the general population. Approximately 6,000 participants will be included, including 3,000 patients with confirmed IBD and 3,000 individuals without IBD serving as a control group. Participants will undergo clinical assessment and routine laboratory testing at baseline and during follow-up visits performed at intervals of approximately three months. The evaluation will include blood tests, urinalysis with measurement of the urine albumin-to-creatinine ratio (ACR), and imaging assessment of the kidneys and urinary tract using abdominal ultrasound. In patients with IBD, disease activity will be evaluated using validated clinical indices, including the Total Mayo Score for ulcerative colitis and the Crohn's Disease Activity Index (CDAI). Fecal calprotectin levels will also be measured to assess intestinal inflammation. The study will also investigate potential associations between renal abnormalities and inflammatory bowel disease activity, pharmacological treatment, and comorbid conditions. Early identification of renal dysfunction may facilitate timely nephrological evaluation and implementation of nephroprotective therapy in affected patients. The results of the NEPHRO-IBD study are expected to improve understanding of renal involvement in inflammatory bowel disease and support the development of strategies for early detection and management of kidney disease in this population.