Role of urinary potassium in ulcerative colitis and its correlation with disease expression: A cross-sectional study

ABSTRACT Background: Environmental factors play an important role in regulating the balance between inflammation and immune tolerance in inflammatory bowel diseases. Potassium may be associated with an anti-inflammatory response. There is limited literature addressing the relationship between potassium and gut inflammatory responses. Hence, this study aims to assess the role of urinary potassium as a marker for ulcerative colitis (UC) disease activity. Methods: A cross-sectional study was conducted on 20 patients with active UC, 20 patients with UC in remission, and 20 subjects as a control group. Clinical and endoscopic disease activity were determined by the Mayo score. A 24-h urinary potassium level was measured, and analysis was performed using an ion-selective electrode Cobas 6000 (Roche) system. Results: Urinary potassium was significantly lower in patients with active UC compared to those with inactive UC and the control group (mean 21.82 ± 26.24 mEq/day vs. mean 46.35 ± 21.42 mEq/day and mean 42.18 ± 5.31 mEq/day, respectively, P < 0.001). Urinary potassium correlated negatively with Mayo score ( P = 0.002), Montreal classification ( P = 0.001), fecal calprotectin ( P < 0.001), and C-reactive protein ( P = 0.001). Receiver-operating characteristic curve showed that urinary potassium can significantly discriminate between active and inactive UC at a cutoff level ≤28.2 mEq/day with 85.0% sensitivity, 75.0% specificity, 77.3% positive predictive value, and 83.3% negative predictive value with 80.0% overall accuracy. Conclusion: A 24-h urinary potassium measurement at a cutoff of ≤28.2 mEq/day could be an effective complementary marker for diagnosing active UC.