Assessment of serum levels of vitamin D and tumor necrosis factor alpha in ulcerative colitis patients at Egyptian Military Hospitals: Cross-sectional observational study.

Ulcerative colitis (UC) is a chronic inflammatory disorder confined to the colonic and rectal mucosa. The disease is marked by infiltration of immune cells, leading to excessive production of inflammatory mediators. A key pro-inflammatory cytokine that plays a vital role in the pathophysiology of ulcerative colitis is tumor necrosis factor alpha (TNF-alpha). Low levels of vitamin D have been associated with several autoimmune disorders. This study aimed to assess vitamin D serum levels in UC patients as regard TNF-alpha serum levels and the Severity of UC (UCDAI). This cross-sectional observational research was carried out at Military healthcare facilities in Cairo, Egypt, over six months, from 1 July 2025 to 31 December 2025. Utilizing a convenience sample of 50 adults aged 15 to 70 years with a confirmed diagnosis of ulcerative colitis, newly diagnosed. They were divided into two groups according to disease severity (UCDAI or Mayo score): 26 patients in the mild group & 24 patients in the moderate/severe group. Demographic data were collected from patients' interviews. Colonoscopy for ulcerative colitis disease activity index (UCDAI) score, CBC, ESR, CRP, and Fecal calprotectin (FC) were investigated at Egyptian Military hospitals. Serum levels of 25-hydroxyvitamin D (using CLIA) and TNF-alpha (using ELISA) were measured at central laboratories of the armed forces and blood bank. Correlation analysis showed Serum Vitamin D had a moderate negative correlation with UCDAI (r = -0.466, p-value= 0.001), and a strong negative correlation with serum TNF-alpha (r = -0.669, p-value <0.001). Serum TNF-alpha showed a moderate positive correlation with UCDAI (r = 0.472, p-value= 0.001). Fecal calprotectin had a strong positive correlation with UCDAI (r = 0.704, p-value <0.001) and a weak positive correlation with serum TNF-alpha (r = 0.388, p-value= 0.005). In conclusion, this study demonstrates that patients with moderate to severe ulcerative colitis had pronounced mucosal and systemic inflammation, reflected by markedly elevated fecal calprotectin and TNF-alpha levels, concomitant with significantly lower vitamin D concentrations compared with those in mild disease.