Secondary Ammonia Scavenge With Glycerol Phenylbutyrate Improves Hyperammonemia Following Portosystemic Shunting

Abstract

Portosystemic shunts are used to treat portal hypertension arising from extrahepatic portal venous obstruction. They decompress the portal system by allowing intestinal blood to bypass the liver and enter directly into the systemic circulation. These shunts increase the risk of minimal hepatic encephalopathy and altered neurodevelopmental outcomes in affected children. Treatment options are limited and have been extrapolated from those used in cirrhosis. We describe the use of glycerol phenylbutyrate as an alternate management strategy. A 3-year-old boy underwent distal splenorenal shunt for refractory variceal bleeding secondary to portal hypertension. He had neurologic deterioration and hyperammonemia refractory to traditional management strategies. Glycerol phenylbutyrate was initiated and resulted in a sustained improvement in ammonia levels, behavior, and school performance. This case illustrates the successful use of glycerol phenylbutyrate in a noncirrhotic patient with Portosystemic shunt and minimal hepatic encephalopathy refractory to conventional management strategies.

Keywords: hepatic encephalopathy; minimal hepatic encephalopathy.

FIGURE 1.

Box plot demonstrating median ammonia values and interquartile ranges before and following initiation of glycerol phenylbutyrate. A) including spurious ammonia values exceeding 100 µmol/L on three occasions post glycerol phenylbutyrate. B) excluding spurious ammonia values exceeding 100 µmol/L on 3 occasions post glycerol phenylbutyrate.