Abstract
A 91-year-old woman with dementia and preserved ADL was admitted to our emergency department because of disturbance of consciousness. She was diagnosed with urinary tract infection associated with urinary retention. Laboratory data revealed dehydration, renal dysfunction, and an increased ammonia level of 119μg/dL, which were thought to be the cause of disturbance of consciousness. She had no past history of hepatic disorder and was taking no medication that would cause hyperammonemia. Urinalysis showed alkalinuria and ammonium magnesium phosphate crystals. These findings indicated that the hyperammonemia was caused by urease-producing bacteria. An indwelling urinary catheter and administration of antibiotics immediately improved the serum ammonia level and promptly improved consciousness. Ammonia produced by urease-producing bacteria accumulated in the bladder, and was absorbed by the venous plexus of the bladder wall. Ammonia entered the systemic circulation without being metabolized in the liver, resulting in hyperammonemia. In patients with dysuria, we should consider the possibility of hyperammonemia caused by urease-producing bacteria as one of the causes of disturbance of consciousness.
