Hyperammonemic encephalopathy requiring hemodialysis in a child with distal renal tubular acidosis.

A 3.5-year-old girl with genetically proven distal renal tubular acidosis presented with lethargy, after numerous episodes of vomiting and poor feeding. Laboratory investigations revealed severe metabolic acidosis, hypokalemia and a serum ammonia level of 515 mmol/L (normal range: 19-50 mmol/L). Despite treatment with sodium bicarbonate, potassium supplementation, sodium benzoate and carglumic acid, her condition required hemodialysis, which resulted in rapid improvement in clinical and metabolic parameters. Hyperammonemia in distal renal tubular acidosis results from impaired ammonium excretion and increased ammoniagenesis due to hypokalemia and chronic metabolic acidosis, particularly during metabolic decompensation. This case had the highest ever reported serum ammonia level in distal renal tubular acidosis with encephalopathic findings, necessitating hemodialysis treatment. Routine monitoring of serum ammonia levels in distal renal tubular acidosis patients during metabolic stress is essential.