Evaluation of radiochromium blood loss studies in unexplained iron-deficiency anaemia.

Radiochromium measurement of gastrointestinal (GI) blood loss was performed on an outpatient basis on 57 patients with unexplained iron-deficiency anaemia. With the exception of pre-menopausal women, patients were only selected for study if the anaemia remained unexplained after careful GI radiological and endoscopic examination. Occult GI blood loss was confirmed in 31 patients and further investigation including laparotomy in some cases, led to a diagnosis in 17 of the 31. Carcinoma was present in five (colon four, stomach one) and benign lesions of the small intestine in five. There was no correlation between the severity or pattern of bleeding and the nature of the lesion. Of the 26 patients without demonstrable occult bleeding, anaemia was aspirin-induced in five and caused by menorrhagia in six. With the pre-menopausal women, measurement of both GI and menstrual blood loss resulted in detection of silent GI lesions in four and gynaecological disease in six. The cause of anaemia has not been elucidated in 23 of the 57 patients, including seven of 11 with aortic valve disease, even after follow-up for an average of 3.0 years. These results indicate that radiochromium studies effectively identify the patients with unexplained iron-deficiency anaemia who require continued active investigation for a focal GI lesion.