LAUSR

www.ccmjournal.org Critical Care Medicine • Volume 46 • Number 1 (Supplement) Learning Objectives: Rare cases have been reported of hyperammonemia after Roux-en-Y gastric bypass (RYGB) and small bowel resection surgeries separately. Here, we discuss a patient with hyperammonemic encephalopathy secondary to RYGB surgery and small bowel resection, complicated by new-onset seizures. Methods: A 45-year-old woman who had RYGB surgery 15 years ago and small bowel resection 5 years prior presented with decreased oral intake, weakness, and altered mental status (AMS). She had a 7-month history of frequent admissions for elevated ammonia levels and AMS, previously treated with rifaximin and lactulose. She was intubated for airway protection. On admission to our ICU, she was found to have an elevated ammonia level of 140 mcg/dL (15–45 mcg/dL) after already receiving rifaximin and lactulose for 4 days. Transaminase levels were normal. Prior liver biopsy was noted to be negative for cirrhosis, but showed fatty liver changes. A previous work-up for Wilson’s Disease was negative. These results increased suspicion for a urea cycle disorder. Serum amino acid levels and urine orotic acid were tested, revealing elevated urine orotic acid at 2.4 mmol/mol Cr (0.4–1.2) and low serum citrulline at 9 nmol/mL (17–46), arginine at 24 nmol/ mL (32–120), and ornithine at 21 nmol/mL (38–130), indicative of a partial ornithine transcarbamylase (OTC) deficiency. Following treatment with lactulose, rifaximin, and a low protein parenteral diet, ammonia levels normalized by hospital day (HD) 8. Mental status improved and she was extubated and downgraded to the hospital floors. On HD10, she was readmitted to the ICU after new-onset tonic-clonic seizures, which resolved with Ativan. Micronutrient deficiency was suspected as the cause. Serum electrolyte levels were not consistent with refeeding syndrome. Serum lab values displayed low levels of zinc, selenium, and vitamin B6. She was placed on phenytoin, lamotrigine, and clozabam. With supplementation of these micronutrients, she has remained seizure free. Results: Although rare, partial OTC deficiency may cause severe complications following RYGB and small bowel resection surgeries, even years after the procedures. Careful dietary formulation as well as replacement of micronutrients due to malabsorptive state is essential in the treatment of these patients.