Salt and water homeostasis during oral rehydration therapy in neonates and young infants with acute diarrhoea. II. Rehydration with a solution containing 90 mmol sodium per litre (ORS90).

The clinical response and changes in water and salt homeostasis were studied during oral rehydration therapy (ORT) with a solution containing 90 mmol sodium per 1 (ORS90) in 9 infants less than 2 months old (range 2-60 days). Two infants were still dehydrated 36 hours after starting ORT and were excluded from the study. Fluid was retained more rapidly and also to a larger extent than in infants of the same age treated with a solution with a sodium concentration of 60 mmol/l (ORS60). The stool sodium output was higher than that found previously in infants of the same age treated with ORS60. We conclude that during ORT the gut plays an active role in the regulation of salt homeostasis. When the sodium intake is high the percentage of sodium remaining unabsorbed is higher than when the intake is low. This mechanism reduces the risk of hypernatremia in young infants treated with ORS90. The study thus demonstrates that ORS90 is effective and also seems to be safe in the treatment of neonates and young infants with dehydration secondary to diarrhoea if fluid intake is kept around 200 ml/kg/day during the rehydration period.