Ornithine transcarbamylase deficiency presenting as encephalopathy during adulthood following bariatric surgery

Background: Neurological complications following bariatric surgery are rare. Whereas nutritional deficiencies are the most common cause of neurological symptoms, the unmasking of previously subclinical metabolic disorders can also lead to significant morbidity. Objective: To characterize the clinical presentation, serum biochemical fluctuations, and functional enzymatic analysis of a case of functional ornithine transcarbamylase deficiency unmasked by a dietary change following bariatric surgery. Design: Case report. Setting: Tertiary referral center, hospital (inpatient) setting. Patient: A 29-year-old woman who presented with intermittent encephalopathy associated with recurrent hyperammonemia. Interventions: Clinical, biochemical, and mutational studies. Results: The pattern of intermittent hyperammonemia and encephalopathy following oral and parenteral nutrition suggested a urea cycle abnormality. Functional enzymatic assay results showed markedly reduced ornithine transcarbamylase activity in the absence of known coding mutations. Conclusion: Previously asymptomatic ornithine transcarbamylase deficiency should be suspected in adult patients who develop recurrent hyperammonemia and encephalopathy following bariatric surgery.