[A case of adult-onset type II citrullinemia triggered by entering a nursing home with a good response to medium-chain triglyceride oil therapy].

A 49-year-old woman with intellectual disability and a food preference for fried chicken entered a nursing home. After nursing home diet, she developed episodic attacks of hyperammonemic encephalopathy. Her characteristic food preference and the negative results for brain and liver imaging studies suggested urea cycle disorder. A high plasma citrulline level on amino acid analysis and a genetic test for citrine gene confirmed a citrine deficiency (adult-onset type II citrullinemia). Although a low-carbohydrate diet was insufficient, a combination therapy of a low-carbohydrate diet and a medium-chain triglyceride (MCT) oil was effective. MCT oil may be a promising treatment option.