Innocent Bystander or Encephalopathic Killer: Hyperammonemia in the Non-Acute Liver Failure Patient

Hyperammonemia is common in critically ill patients and many clinicians are left to wonder is this the cause of AMS, a bystander, or a biomarker of more sinister pathology. Although acute liver failure is easily diagnosed, hyperammonemia in the non-liver failure patient may be a marker of infection or inborn errors of metabolism that need to be identified and treated.  We discuss both the workup to the non-liver failure hyperammonemic patient as well as a why and how hyperammonemia should be treated in the patient with AMS.