Abstract | November 6, 2020
High Ammonia, And It’s Not The Liver?
Learning Objectives
- To identify the non hepatic causes of elevated ammonia levels , which are not discussed often.
- To create awareness that elevated ammonia levels may be a side effect of several surgical procedures and have a high degree of suspicion for hyperammonemia if such patients present with altered mental status.
Introduction: Roux-en-Y gastric bypass is the most commonly performed bariatric surgery. Hyperammonemia as a complication of this surgery is poorly understood.
Case Presentation: A 63 year old woman with Roux-en-Y gastric bypass surgery presented 3 months prior to the current admission with progressively declining functional and cognitive status. Workup revealed elevated ammonia levels with normal liver functions. Liver biopsy showed non-alcoholic steatohepatitis without cirrhosis. Lactulose was initiated. She was transferred to a psychiatric facility due to neuropsychiatric symptoms.Following minimal improvement, she was discharged.
This admission, she was in septic shock and required mechanical ventilation. History was limited since family and records were unavailable. Physical exam revealed anasarca. Labs showed anemia, neutrophilic leukocytosis, acute kidney injury. Albumin was 1.0gm/dl, AST- 40U/L, ALT- 60U/L, ALP- 180U/L, total bilirubin- 1.4mg/dl. CT brain was normal.
On day 3, oxygenation improved, shock and AKI resolved. However, she continued to be obtunded off sedation. She developed continuous myoclonic jerks. EEG revealed generalized epileptiform discharges. Ammonia level was elevated at 543 mmol/l while liver function tests( LFTs) were normal.
Working diagnosis: Urease producing bacteria and medications like valproate were excluded. Other non-hepatic causes of hyperammonemia such as inborn errors of metabolism, total parenteral nutrition, gastric bypass were being considered.
Management and follow up: Myoclonic jerks remained uncontrolled with anti-epileptics and other sedatives. Elevated ammonia levels with normal LFTs prompted further investigation. Given her surgical history, gastric bypass was considered as the most likely etiology . Less than 30 cases of hyperammonemia due to gastric bypass have been reported. Symptoms can occur from months to years following surgery. Literature review showed that lactulose, rifaximin, reversal of gastric bypass and hemodialysis have all been tried. Unfortunately this condition has poor prognosis and is usually fatal. Given her decline, family withdrew care and patient eventually succumbed.
