A prospective study of persistent diarrhoea.

A prospective study was undertaken in 100 patients with diarrhoea to identify the causes and to better define the prevalence of the irritable bowel syndrome (IBS) and to determine if there was a diagnostic symptom complex evident in patients with IBS. A diagnosis of IBS was made in 28 patients and in this group the prevalence of lactase deficiency was found to be 40%. Pain in association with urgency was usual and urgency occurring in the absence of pain was more likely to be found in association with an organic colonic lesion. The two most important symptoms which distinguish IBS from other causes were blood in the motions and weight loss. Giardia lamblia were found in nine patients and 15 patients responded to an empirical course of either metronidazole or tinidazole, without a positive diagnosis of giardiasis being made. Fourteen patients had inflammatory bowel disease and a variety of drugs were responsible for diarrhoea in 10% of patients. Sigmoidoscopy and small bowel biopsy were the most valuable diagnostic investigations.