Congenital sodium diarrhea in a neonate presenting as acute renal failure.

Congenital sodium diarrhea is a rare cause of secretory diarrhea due to a defect in the sodium/proton exchanger that results in decreased sodium absorption and increased excretion in stools. We report a pre-term baby boy with a birth weight of 1.4 kg who was referred because of rapidly rising serum urea and creatinine. The initially reported high urine output was later found to be severe watery diarrhea with severe oliguria and acute renal failure. Associated findings were normal anion gap metabolic acidosis with hyponatremia that required > 50 mmol/kg of sodium per day for correction and about 300 ml/kg per day of replacement fluid to correct fluid and electrolyte abnormalities. The patient continues to do well 5 months after diagnosis.