A case of hyperammonemia due to urinary tract infection complicated by hypothyroidism

Abstract

We report a case of disturbance of consciousness due to hyperammonemia stemming from urinary tract infection with urease-producing bacteria and complicated with hypothyroidism. An 84-year-old woman visited her family doctor with a history of excessive fatigue and was prescribed ciprofloxacin hydrochloride for cystitis and sulpiride for depression. The following day, she was brought to our hospital in an ambulance because of disturbance of consciousness. Sulpiride poisoning was suspected, and she was admitted to our emergency department. Because blood tests suggested hyperammonemia (197 μg/dl) and hypothyroidism, she was administered Lactulose, branched-chain amino acids, and thyroid hormones. Neither liver disease nor portosystemic shunting was observed in the blood or the imaging tests. The consciousness level initially improved along with the ammonia levels, however it later deteriorated again as the ammonia levels increased. Because urinary tract infection was complicated, we started administering antimicrobials. As a result, the level of ammonia normalized, and the level of consciousness improved. Arthrobacter cumminsii was detected by urine culture. Thus, we made a diagnosis as hyperammonemia due to urinary tract infection with urease-producing bacteria. In addition, hypothyroidisim in the patient aggravated hyperammonemia. In cases of hyperammonemia unaccompanied by liver disease, urease-producing bacterial infection and/or hypothyroidism should be considered.