Body composition in ileostomy patients with and without ileal resection.

Body composition was measured in 24 patients who had previously undergone proctocolectomy and ileostomy. One group (control group) had undergone resection of only small amounts of terminal ileum (median 4 cm), the other group of patients (resected group) had undergone resection of greater lengths of small bowel (median 54 cm). These values of body composition were then compared with predicted values in normal subjects. Proctocolectomy and ileostomy without ileal resection did not significantly affect body weight, or the body contents of fat or water, but led to a reduction in total body nitrogen and total body potassium, suggesting a reduction in fat free mass. A modest resection of the terminal ileum undertaken during the course of proctocolectomy decreased body weight largely because of a reduction in body fat. None of the ileostomy patients was found to be dehydrated.