Abstract
A 69-year-old man was admitted to our intensive care unit because of a disturbance in consciousness. He had been diagnosed as having type II diabetes at the age of 24 years but had not developed severe liver dysfunction. A plain abdominal CT showed left pyelonephritis and an expanded left renal pelvis as a result of ureteral stones. A laboratory investigation revealed hyperammonemia. A cranial MRI showed edematous changes in bilateral thalamus and bilateral insula, supporting a diagnosis of hyperammonemia. After the placement of a left ureteral stent, the patient's consciousness level reversed and his plasma ammonia level returned to normal. Proteus mirabilis, a urea-metabolizing bacteria, was cultured in blood and urine samples from the patient. The production of urease by bacteria in the urinary tract probably hydrolyzed the urinary urea, producing ammonia. We suspect that the source of the disturbed consciousness in the present patient might have been hyperammonemic encephalopathy caused by the absorption of ammonia produced by bacteria in the retained urine into the systemic circulation.
