"Neonatal variant" of Bartter syndrome presenting with acidosis.

An infant is reported with the "neonatal variant" of Bartter syndrome, presenting at 5 weeks of age with metabolic acidosis associated with a life-threatening water and electrolyte depletion. Alkalosis was first shown after 2 weeks of vigorous fluid, sodium, and potassium substitution. We suggest that the extreme fluid and electrolyte losses associated with the "neonatal form" of Bartter syndrome could lead to acidosis more often than previously suspected, and may cause underdiagnosis of a possibly fatal condition.