Background and study aim: Ulcerative colitis (UC) belongs to the chronic inflammatory diseases with unknown etiology. At present, the diagnosis and monitoring of UC, tracking of responses to intervention, and detection of mucosal healing depend on endoscopy. However, it is invasive, expensive, and requires colonic preparation. We aimed to investigate the clinical roles of anti-PR3-ANCAs in the disease diagnosis and disease severity of ulcerative colitis patients.
Patients and Methods: This study was conducted on 50 UC patients attending Kafrelsheikh University Hospital, 13 intestinal control group, and  17 age and sex-matched healthy volunteers from  May 2023 to May 2024,  colonoscopy and evaluation of (Anti PR3-ANCAs) were done in each group.
Results: forty-one patients were PR3-ANCA positive, of them 18 patients were recently diagnosed, while 20 patients were treated for more than one year, and 3 patients were treated for less than one year. The cut-off value for PR3-ANCA to predict ulcerative colitis was >3.3 U/mL with sensitivity 84.0%, specificity 77.0%, area under the curve (AUC) 0.906, 95% confidence interval (CI) (0.839–0.972), p =0.000.
Conclusion: PR3-ANCA has an important role as a diagnostic biomarker for UC and in assessing the disease severity.