The clinical manifestations of
hyperammonemia are usually easily identifiable to the clinician when associated with
liver disease and lead to prompt diagnosis and treatment. However,
hyperammonemia-induced
encephalopathy is rare in adults in the absence of overt
liver disease, thus diagnosis is often delayed or missed leading to potentially life threatening complications. Without proper treatment, such patients can decompensate rapidly with poor outcomes including
seizures,
coma, and death. Early assessment of plasma
ammonia levels in patients with normal hepatic function and characteristic symptoms of
encephalopathy can lead to early intervention while investigating the underlying etiology. We describe a patient who presented with a 2-year progression of waxing and waning acute mental status changes after a
Roux-en-Y gastric bypass surgery. He was found to have elevated
ammonia level as well as orotic aciduria; results consistent with a
urea cycle disorder. After consulting neurology as well as toxicology, he ultimately improved after
dietary protein restriction,
sodium benzoate and
lactulose therapy. While rare, clinicians should have a high index of suspicion for late onset
urea cycle disorders in symptomatic patients presenting with
encephalopathy secondary to
hyperammonemia.