DETERMINANTS OF DECREASED FECAL CONSISTENCY IN PATIENTS WITH DIARRHEA

Background/Aims: Loose stools are a common and troublesome feature in diarrhea. The purpose of this study was to investigate factors that de termine different degrees of stool looseness in diarrhea. Methods: Fec al consistency was measured visually. Stools were analyzed for content of water and solids. Water-holding capacity of insoluble solids was m easured in vitro. Results: Formed stools from normal subjects had a ne ar constant ratio of water to solids despite a sevenfold variation in daily stool weight. In diarrhea, loose consistency was correlated dire ctly with percent fecal water. For any level of percent water, steator rhea stools were looser than nonsteatorrhea stools. Ingestion of psyll ium reduced stool looseness without changing the percent water. Both t he effect of fat and psyllium could be explained by consideration of t he ratio of fecal water to water-holding capacity of insoluble solids. Conclusions: (1) The normal intestine delivers stools that differ wid ely in quantity but maintains percent fecal water within a narrow rang e. (2) Stool looseness in diarrhea is determined by the ratio of fecal water to water-holding capacity of insoluble solids. (3) In patients with diarrhea with normal stool weight, loose stools are due to low ou tput of insoluble solids without the concomitant reduction in water ou tput that occurs in normal subjects when insoluble solids are low.