1. Most subjects who have their large intestine removed and an ileostomy formed lead a healthy life after operation, although they are prone to a variety of metabolic problems. In order to determine the factors likely to lead to these metabolic disturbances a detailed assessment of ileostomy output and composition and of dietary intake in relation to nutritional and metabolic status has been made in a group of ileostomy patients living at home.
2. Thirty-six volunteers with established ileostomies (twenty-six ulcerative colitis (UC) patients and ten, Crohn's colitis (CC) patients) made a 24 h collection of urine and ileostomy effluent and kept a 7 d record of dietary intake and the frequency with which they emptied their ileostomy bag. Blood was collected for haematological and biochemical indices of nutritional status and height, weight and skinfold thickness were measured.
3. Effluent output for the whole group was 760±322 g/day (range 273–1612) and was very closely related to effluent sodium output (R 0·98). Stepwise multiple regression analysis of dietary and other variables identified the amount of ileum resected as the main determinant of both effluent output and effluent sodium. The CC group had significantly greater effluent output (1084±340 g/d) compared with the UC patients (635±215g/d) (P < 0·001); and excreted significantly more nitrogen, carbohydrate and sodium than the UC group.
4. The CC patients particularly showed evidence of salt depletion. The mean (±SD) 24 h urine Na loss for CC patients was 31±30 mmol and for UC patients 67±34 mmol (P < 0·01) with five of the ten CC patients v. four of the twenty-six patients with UC having raised urinary or plasma aldosterone levels.
5. All subjects had normal haematological and biochemical indices of nutritional status in the blood. Height and percentage body fat were also within the normal range when compared with a control population matched for age, sex and occupation, but patients with an ileostomy weighed on average 4·1 kg less than the controls.
6. These studies show that patients with an ileostomy come within the range of the normal population for most nutritional indices although are at increased risk of salt depletion. Effluent volume, which is probably the determining factor in most metabolic complications of ileostomy, is related more to the extent of the small bowel resection than to diet.