Measurement of blood and iron loss in colitis with a whole-body counter.

Estimation with a whole-body counter of the fall in total body radioactivity due to loss of parenterally administered (59)Fe has been used to measure blood loss in 17 patients with ulcerative colitis. It was shown that blood loss was related to the activity of disease as judged by sigmoidoscopic changes and less obviously to the extent of involvement of the colon. Blood losses of 50 to 150 ml per week were observed when the patient saw no blood in the stools and the rectal mucosa did not appear haemorrhagic. Some patients lost more than 0.5 g iron during the few weeks following an exacerbation of ulcerative colitis suggesting that repeated replacement of the body's iron stores is often necessary in this disease.