Abdominal pain continues to be a common chief complaint in the emergency setting. While this presentation can be non-specific, there are certain findings that warrant immediate surgical intervention. Portal venous gas on imaging in the setting of peritonitis and sepsis is one such finding. Thyrotoxicosis on the other hand is an uncommon diagnosis that is associated with non-specific symptoms resulting in delayed diagnosis, a clinical scenario that can lead to significant morbidity and mortality. Here, we present a rare case of a patient who presented with signs and symptoms of peritonitis and portal venous gas on CT scan that was taken emergently to the operating room. No intraabdominal pathology was identified. The patient was later diagnosed with thyrotoxicosis, the presumed cause of the acute abdomen presentation.