CONGENITAL CHLORIDE-LOSING DIARRHEA - ABSENCE OF THE ANION-EXCHANGE MECHANISM IN THE RECTUM

Background: Congenital chloride-losing diarrhoea is characterized by a defect in chloride/bicarbonate exchange, which is normally present in the ileum and colon. Whether the defect is an absence or a reversal o f such an exhange is unclear, and we have investigated two young child ren with the disorder to answer this question. Methods: We used a prev iously described nonequilibrium rectal dialysis method, using differen t dialysate anion concentrations, to investigate the movement of sodiu m, potassium, chloride, and bicarbonate in the rectum of the two child ren. Results: The results showed that chloride and bicarbonate movemen ts were not linked in any active way, and both ions appeared to move p assively in response to the electrochemical gradients generated. Concl usions: In the two subjects studied, the defect in the rectum appears to be an absence of the normal anion exchange mechanism present in the bowel, rather than its reversal.