Objective: Studies have found increased expression of IL-23 in inflamed and non-inflamed mucosa of patients with ulcerative colitis (UC). We hypothesized that serum interleukin-23 as a non-invasive test has a role in pathogenesis of ulcerative colitis disease and correlates with the disease severity.

Methods: Forty patients with biopsy proven ulcerative colitis, recruited from Ain Shams University hospitals were included. Forty healthy subjects matched in age and gender were also included in the study as a control group. Serum IL-23 level was quantified using quantitative ELISA technique (Enzyme linked Immunosorbent Assay).

Results: Patients with UC had higher level of interleukin 23 (234.5 ± 161 pg/mL) compared to control subjects (54.2 ± 15 pg/mL) and the level of IL-23 correlated with the disease severity. Cut off value of IL-23 at 68 pg/mL was the best to differentiate between cases and control subjects. Receiver operating characteristic curve (ROC) revealed that the best cut off for IL-23 to detect mild cases of ulcerative colitis was at105 pg/mL, to detect moderate cases at 200 pg/mL and to detect severe cases was at 270 pg/mL with sensitivity 80% to mild cases, 60% to moderate cases and 81% to severe cases.

Conclusions: Our findings confirm the suggestion that IL-23 level measurement may be of value as a non-invasive test in the diagnosis and disease severity assessment in patients with UC.