Oral Sodium Phenylbutyrate For Hyperammonemia Associated With Congenital Portosystemic Shunt: A Case Report

Objectives: The efficacy of sodium phenylbutyrate (SPB) for hyperammonemia associated with congenital portosystemic shunt (CPSS) remains unknown. We show the effectiveness of oral SPB.Case presentation: Our patient had CPSS with severe hypoplasia of extrahepatic portal veins. At 9 months of age, to assess the efficacy of oral SPB, we evaluated the 24 h fluctuations of venous ammonia levels. In the first two days without SPB, ammonia levels were above 80 mu mol/L for half a day. On the third and fourth days, administration of oral SPB three times a day decreased ammonia to acceptable levels, except at midnight. On the fifth day, another oral SPB administration at 8 pm decreased ammonia at midnight. Low levels of branched-chain amino acids, as well as coagulation disturbances, were observed without apparent symptoms. At 12 months of age, he showed normal psychomotor development.Conclusions: Oral SPB may be effective for hyperammonemia associated with CPSS.