Abstract: Objective To measure serum 25-carboxyvitamin D levels and vitamin D1-α-hydroxylase （CYP27B1） expression levels in elderly patients with inflammatory bowel disease （IBD） and their correlation with the severity of the disease. Methods All patients aged ≥60 years, diagnosed with IBD and treated in the Department of Gastroenterology, the Fourth People‘s Hospital of Zigong City from 2015 to 2018 were included in the study. The elderly people who underwent physical examination at the same period were selected as the control group. Serum 25-hydroxyvitamin D levels and CYP27B1 expression of the two groups were analyzed. Results Ninety-three elderly patients with IBD were enrolled in the study, including 58 males and 35 females, with an average age of （64.7 ± 5.1） years. Fifty persons were selected in the control group, including 31 males and 19 females, with an average age of （63.7 ± 4.8） years. There were no significant differences in mean age and gender composition between the two groups （P>0.05 for both）.Forty-eight patients were diagnosed with ulcerative colitis （UC） and 45, with Crohn’s disease （CD）. Levels of 25-hydroxyvitamin D in patients with UC, patients with CD and control group were （11.06 ± 4.14）, （12.51 ± 4.77）, （16.26 ± 5.23） ng/mL, respectively, and the IHC scores of CYP27B1 expression were （9.5 ± 1.1）, （9.3 ± 1.3）, and （3.4 ± 0.6）, respectively （P<0.01 for all）. A negative correlation was observed between the level of 25-hydroxyvitamin D and the disease activity score （r=-0.325, -0.382）, while the IHC score of YP27B1 was positively correlated with the disease activity score （r=0.413, 0.371）. Conclusion Serum 25-carboxy vitamin D level in elderly IBD patients was significantly lower than that in normal population, while CYP27B1 expression was higher than that in normal population and correlated with the severity of the disease.

Key words: Inflammatory bowel disease, 25-carboxy vitamin D, Vitamin D1-hydroxylase, Elderly patients