Hyperammonemia in a Patient with Late-Onset Ornithine Carbamoyltransferase Deficiency

Ornithine carbamoyltransferase (OTC) deficiency is a urea cycle disorder that causes the accumulation of ammonia, which can lead to encephalopathy. Adults presenting with hyperammonemia who are subsequently diagnosed with urea cycle disorders are rare. Herein, we report a case of a late-onset OTC deficient patient who was successfully treated with arginine, benzoate and hemodialysis. A 59-yr-old man was admitted to our hospital with progressive lethargy and confusion. Although hyperammonemia was suspected as the cause of the patient's mental changes, there was no evidence of chronic liver disease. A plasma amino acid and urine organic acid analysis revealed OTC deficiency. Despite the administration of a lactulose enema, the patient's serum ammonia level increased and he remained confused, leading us to initiate acute hemodialysis. After treatment with arginine, sodium benzoate and hemodialysis, the patient's serum ammonia level stabilized and his mental status returned to normal.

Intermittent hyperammonemic encephalopathy in a child with ornithine transcarbamylase deficiency.

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder and the most common inherited cause of hyperammonemia. Clinical manifestations are more severe in hemizygous males who often present in neonatal period. Heterozygous females may be asymptomatic until juvenile or adulthood. Fluctuating concentration of ammonia, glutamine and other excitotoxic amino acids result in a chronic or episodically recurring encephalopathy. The authors report a heterozygous female with OTC deficiency who presented with recurrent encephalopathy.