A case of adult-onset type II citrullinemia in an elderly patient

A 72-year-old man presented with consciousness disturbance. The results of brain magnetic resonance imaging and cerebrospinal fluid examination were normal, but triphasic waves were noted on electroencephalography. His plasma ammonia level was elevated due to which encephalopathy secondary to hyperammonemia was suspected. However, his liver function was normal, and no evidence of cirrhosis or portal-systemic shunt was noted. The patient's medical history revealed that he had a tendency to excessively consume pulse products since childhood, and an amino acid analysis showed elevation of citrulline and arginine levels. Thus, we diagnosed the patient with an extremely rare case of adult-onset type II citrullinemia, which was triggered by cessation of the intake of pulse foods (soybeans and peanuts) due to dental problems.