'All that glitters is not gold': when hyperammonaemia is not from hepatic aetiology.

Hyperammonaemia is often caused by decompensated liver disease. However, non-hepatic causes can sometimes result in hyperammonaemia, severe enough to cause symptoms.We report a case of a 65-year-old man with a history of hypertension and bilateral peripelvic renal cyst who presented with acute confusion. Laboratory investigations revealed hyperammonaemia and normal liver function test. The abdominal ultrasound did not reveal any finding of liver disease or portal-systemic shunting but demonstrated bilateral peripelvic cysts with no hydronephrosis.Hyperammonaemia was attributed to urinary tract infection with a urea-splitting Escherichia coli bacterium.Antibiotic therapy and lactulose were administered. His neurological status rapidly normalised over the next 48 hours, concomitantly with a decrease in ammonia level. Clinician awareness of non-hepatic causes of hyperammonaemic encephalopathy like urinary tract infection can contribute to early diagnosis and timely initiation of appropriate and potentially life-saving treatment including antimicrobial therapy, alleviating urinary obstruction, if present, and lactulose. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.