P4828 - Think Outside the Box! Not All Hyperammonemia is Due to Liver Disease

Luis G. Santiago Zayas, MD¹, Alisha Menon, MD¹, Ambar Sekulits, MD², Saadia Nabi, MD¹, Savier Aleman Rama, MD¹, Ramasamy Nathan, MD^1
1Aventura Hospital, Aventura, FL; ²Aventura Hospital, Dania Beach, FL

Introduction: Urea cycle disorders (UCDs) represent a subset of inborn errors of metabolism characterized by defects in ammonia detoxification pathways. Patient with UCD face a risk of hyperammonemia, marked by a spectrum of symptoms including headaches, vomiting, psychosis, ataxia, seizures, altered mental status, and coma. If untreated, hyperammonemia will result in encephalopathy, cerebral edema, coma and death. Here we present a unique case of encephalopathy in a patient with a known urea cycle disorder.

Case Description/Methods: A 36-year-old female with a medical history of Ornithine Transcarbamylase deficiency (OTC) presented to the emergency department with psychosis symptoms and weakness for 1 to 2 days. Patient was noted to be agitated, disoriented (Glasgow Coma Scale 13) with tachycardia and significant asterixis. Her initial laboratory results were significant for an elevated ammonia level of 453 and the arterial blood gas revealed a respiratory alkalosis (pH 7.466, pCO2 24.2, and HCO3 17.1 mmHg). Liver synthetic function tests were normal. The patient was given intravenous dextrose 10% with hypotonic normal saline, a low protein diet, and her home glycerol phenylbutyrate. The next day, the patient showed significant neurological improvement with an improvement in her ammonia levels.

Discussion: In the urea cycle, 6 enzymes are involved in the conversion of ammonia to urea, the most common deficiency being OTC. Complete deficiency will lead to symptoms in infancy whereas partial deficiency can lead to delayed symptoms in adulthood. The incidence of OTC is 1 in 35,000 liver births, inherited by an X-linked mechanism. These patients will not respond to oral lactulose or rifaximin unlike in cases of hepatic encephalopathy. Detailed history, genetic testing, and a markedly abnormal increase of orotic acid excretion after an allopurinol challenge test will clinch the diagnosis of OTC. Urea cycle disorders should be considered in patients who present with neuropsychiatric symptoms in the emergency room with hyperammonemia. A prompt recognition of symptoms will prevent permanent neurological damage or even death.


Disclosures:


Luis G. Santiago Zayas, MD¹, Alisha Menon, MD¹, Ambar Sekulits, MD², Saadia Nabi, MD¹, Savier Aleman Rama, MD¹, Ramasamy Nathan, MD¹. P4828 - Think Outside the Box! Not All Hyperammonemia is Due to Liver Disease, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.