Ileostomy Observation Study

Inflammatory bowel disease (IBD) which is associated with low bone mineral density is divided into 2 major disease entities: Crohn's disease and ulcerative colitis. Medical therapy is directed at controlling symptoms and reducing the underlying inflammatory process. Studies have reported that 60% of patients with Crohn's disease and 15%-30% of patients with ulcerative colitis require surgical intervention for the management of their disease. In the United Kingdom almost 13,000 ileostomy procedures are undertaken annually. A 29.4% prevalence of low bone mineral density (BMD) was reported in a cohort of US patients with IBD and ileostomy who were >5 years postoperative. Possible risk factors for bone loss in patients with IBD and ileostomy are considered to include malabsorption secondary to bowel resection, malnutrition and more aggressive disease and inflammation which led to bowel resection in the first place . These factors also contribute to reduced intestinal absorption of nutrients and vitamins including B \& D subsequently leading to potential health complications including low BMI and low lean body mass. It has been reported that IBD patients who have surgical intervention to create ileal pouches also have low levels of vitamin D.

Surgical procedures such as an ileostomy alter the normal anatomy and physiology of the small intestine. Bile acid (BA) malabsorption which is common to IBD is caused by impaired conjugated BA reabsorption and a consequence, numerous pathological sequelae may occur, including the malfunction of lipid digestion . Further, bacterial overgrowth can lead to deconjugation of bile salts, leading to formation of free bile acids, again inducing dietary fat malabsorption, which in turn can lead to vitamin D deficiency. As vitamin D is a fat-soluble vitamin, malfunction of lipid digestion or absorption is problematic.

Given the paucity of data in the area of ileostomy patients BMD, vitamin D status and calcium intake, we will establish baseline observations within the Northern Ireland (NI) population with an observational study to assess bone mineral density (Dexa), collecting ileal fluid and plasma samples assessing vitamin D status, calcium, dietary intake and other measures including questionnaires on quality of life and exercise.