Introduction: Mesalazine, a 5-aminosalicylic acid derivative, is widely used for the induction and maintenance of remission in ulcerative colitis. Because the drug and its metabolites are primarily eliminated through renal excretion, potential nephrotoxic effects during long-term therapy remain a clinical concern. This study aimed to evaluate the relationship between the dose and duration of mesalazine therapy and renal function parameters as well as urinary protein indices in patients with ulcerative colitis. Methods: This retrospective cross-sectional study was conducted at the Gastroenterology outpatient clinic of Karaman Training and Research Hospital, Türkiye. Medical records of patients with ulcerative colitis who attended the clinic between January 2025 and January 2026 were reviewed. A total of 73 patients aged ≥18 years were included. Patients with systemic comorbidities or those receiving potentially nephrotoxic medications were excluded. Clinical and laboratory data were obtained from hospital records. Renal function tests and spot urine parameters were evaluated, and urinary protein-to-creatinine and albumin-to-creatinine ratios were calculated. Statistical analyses were performed using Jamovi statistical software. The study was approved by the Karamanoğlu Mehmetbey University Faculty of Medicine Ethics Committee. Results: The median duration of mesalazine therapy was 9 years and the median daily dose was 1.71 g. Newly diagnosed patients demonstrated significantly higher systemic immune-inflammation index values compared with follow-up patients. However, serum urea, creatinine, and estimated glomerular filtration rate values were comparable between groups. Similarly, spot urine protein, microalbumin levels, and creatinine-indexed urinary protein excretion parameters did not differ significantly. Conclusion: Renal function appears to remain largely preserved in patients with ulcerative colitis receiving mesalazine therapy. Nevertheless, periodic monitoring of renal function is recommended during long-term mesalazine treatment.
Akincioglu et al. (Thu,) studied this question.