[Exploration of the adult patient with chronic diarrhea]

This article describes the clinical approach to the aetiological diagnosis of chronic diarrhoea in adults, with a rational ranking of investigations starting with methodical questioning and careful physical examination. The purpose of the clinical stage is to find out whether the diarrhoea is truly chronic--and not the paradoxical diarrhoea so common in constipated subjects--, to evaluate its repercussions on nutrition and hydration, to try and determine its type (malabsorption or watery diarrhoea) and to elicit an obvious or probable cause. The paraclinical stage includes screening or confirmatory examinations separating watery diarrhoeas (due to colonic hypermotility or secretory of organic origin--mainly colonic, humoral or neurological--or functional origin) from malabsorption diarrhoeas; concerning the latter, the use respiratory tests with hydrogen is emphasized and conventional tests (D-xylose, assay of faecal fats and nitrogen) are mentioned.