Citrulline for urea cycle disorders in Japan

Background The amino acid l ‐citrulline is used as a therapeutic agent for urea cycle disorders ( UCD ) including ornithine transcarbamylase deficiency ( OTCD ), carbamoyl phosphate synthetase I deficiency ( CPSD ), and N ‐acetylglutamate synthase deficiency. There are few reports, however, on the use of l ‐citrulline in Japan and little consensus regarding the effects of l ‐citrulline. Methods We conducted a questionnaire survey of patients undergoing l ‐citrulline treatment for a UCD to evaluate the current status of this therapy. The survey included patient background, details of l ‐citrulline treatment, clinical examination data, treatment, frequency of vomiting, and liver transplantation. Results We retrospectively investigated 43 questionnaire respondents ( OTCD , n = 33; CPSD , n = 10). The weight of male OTCD patients improved by +0.79 SD , and the ammonia level decreased by a mean of 44.3 μmol/L in all patients. The protein intake of all patients and of male OTCD patients increased by 0.14 g/kg/day and 0.17 g/kg/day, respectively. Conclusions l ‐Citrulline effectively reduced ammonia level, increased protein intake, and improved weight gain in UCD patients. l ‐Citrulline should be considered a standard therapy in OTCD and CPSD patients.