CRRT in Nonhepatic Hyperammonemic Encephalopathy After Roux-en-Y Gastric Bypass

Introduction: Severe hyperammonemia is a medical emergency warranting prompt testing and treatment. Serum levels more than 150 umol/L increase the risk of intracranial hypertension which can lead to cerebral edema, coma, seizures, and death. Liver disease is a common cause of ammonia production. However, non-hepatic etiologies of hyperammonemia are often overlooked. Our case highlights the diagnostic workup in identifying the non-hepatic culprit. Additionally we discuss the role of continuous renal replacement therapy (CRRT) in ammonia clearance. Case Description: A 54 year old female with a past medical history of Roux-En-Y gastric bypass in 2000 with revision of jejunojejunostomy anastomosis in 2024 presented to the Intensive Care Unit for encephalopathy and diffuse exfoliative skin lesions. On physical exam, the patient was only responsive to noxious stimuli. Therefore, she was intubated for airway protection. The patient had 4 mm pupils bilaterally and a right sided gaze deviation concerning for elevated ICP. She was hypotensive (BP 88/57 mmHg) and tachycardic (HR 121). Labs were significant for arterial ammonia of 261 umol/L and albumin of 1.7 g/dL. Fortunately, CT Head was negative for acute large vessel occlusion, hemorrhage, or mass effect. EEG was negative for seizures. To manage the ammonia a dialysis catheter was placed and emergent CCVHD was initiated. The initial dialysis prescription had an effluent rate of 69 ml/kg/hr (dialysate flow rate of 5,000 ml/hr and ultrafiltrate 50 ml/hr). The next day, ammonia decreased to 175 umol/L. Further investigation revealed elevated serum glutamine/citrulline with depleted zinc, copper, vitamin B6, and many branched/essential amino acids. After nutrient and vitamin supplementation, L-carnitine, arginine, sodium phenylbutyrate and lactulose, the arterial ammonia normalized within two weeks. The patient was extubated after five days. Discussion: Our patient suffered from severe hyperammonemic encephalopathy and acrodermatitis enteropathica secondary to Roux-En-Y related malnutrition. Ammonia levels were reduced via prompt initiation of high flow CVVHD. This was successful in avoiding cerebral edema. Clinicians faced with a similar clinical case can consider dialysis as an initial therapy. Future research should focus on understanding the role of CRRT dose, timing, and modality in management of patients with hyperammonemia.