Large pulmonary arteriovenous malformation with hyperammonemia.

A 45-year-old female presented with generalized fatigue, unaccompanied by other symptoms. Investigation revealed severe anemia due to gastric bleeding, and hereditary hemorrhagic telangiectasia accompanied by a large pulmonary arteriovenous malformation (PAVM). Additionally, the presence of hepatic arteriovenous and portovenous shunts indicated hepatic involvement. In addition to hypoxemia due to right-to-left shunting in PAVM, hyperammonemia with normal hepatic function was detected. The large PAVM was successfully managed with surgical resection. Hyperammonemia, persisting despite the hemostasis of gastric bleeding, improved postoperatively in the absence of treatment directed at hepatic involvement. We believe that resection of large PAVM contributed to the improvement of hyperammonemia.