Oral rehydration therapy

Oral rehydration solution (ORS), the best treatment of dehydration due to acute diarrhea, is the most important medical advance of this century since it is key to reducing infant and child morbidity and mortality. Pathogens responsible for acute diarrhea include those which produce enterotoxin at the intestinal mucosal surface, inducing secretion but are not invasive (e.g., Vibrio cholerae); those which invade and disrupt the mucosal lining (e.g., shigella species); and rotavirus. The World Health Organization (WHO)/UNICEF ORS is considered a universal ORS. Much research has been done on the ideal composition of an ORS. An ORS must have sufficient sodium to replace losses on a volume to volume basis, a glucose concentration that matches that of sodium to ensure its delivery to the ileum, sufficient amounts of potassium and base (e.g., sodium bicarbonate or trisodium citrate dihydrate) to correct acidosis and to enhance sodium absorption, and sufficient amounts of liquid. The risk of hypernatremia with use of the WHO/UNICEF ORS is a concern since infants and young children have an immature renal concentrating capacity, increased insensible water losses, and an impaired natriuretic response. Neonates and young infants may be prone to relatively slow correction of acidosis. It appears that the potassium content (20 mmol/l) of WHO-ORS should be higher to promote a net positive potassium retention. Too much glucose in the ORS will induce reverse osmosis of water into the gut, effectively making the ORS a dehydrating solution rather than a hydrating solution. Some carbohydrates other than glucose have proven effective glucose substitutes (e.g., sucrose, rice starch and powder, other cereals). Cereals have higher acceptability levels in developing countries. Research is investigating the nutritional benefits of supplementing ORS with micronutrients (e.g., vitamin A, folic acid, and zinc). ORS use with early refeeding has a beneficial effect on nutritional status after an acute diarrhea episode.