Acute hyperammonemic encephalopathy in adult onset ornithine transcarbamylase deficiency

Abstract

Objectives: To report the clinical manifestations of acute hyperammonemic encephalopathy in adult onset ornithine transcarbamylase deficiency (OTCD).

Design: Case report.

Setting: Intensive care unit of a tertiary medical centre.

Patient: A 48-year-old Caucasian male body builder who developed acute loss of consciousness after a febrile illness.

Interventions: The patient was immediately started on hemodia-filtration, protein elimination and ammonia scavenging medications.

Measurements and results: Serum ammonium was elevated and plasma and urine amino acids had a pattern indicative of a urea cycle defect. DNA studies revealed a mutation of the urea cycle enzyme, ornithine transcarbamylase. The encephalopathy resolved and the patient slowly recovered though with some cognitive impairment.

Conclusions: Adult presentation of OTCD is rare and the mortality and morbidity rates are high. However, survival is possible with rapid correction of hyperammonemia. As the clinical manifestations are non-specific, a high index of suspicion is necessary for the correct diagnosis and management.