Uncontrolled Primary Hypothyroidism Precipitating Non-cirrhotic Hyperammonemia: A Unique Interplay Between the Liver and Thyroid.

Hepatic encephalopathy is typically seen in advanced liver disease and in patients with a transjugular intrahepatic portosystemic shunt. Common triggers include infections, gastrointestinal bleeding, electrolyte disturbances, dehydration, and drug/toxin use such as benzodiazepines and alcohol. In rare instances, other metabolic abnormalities such as hypothyroidism may also exacerbate hyperammonemia in patients with underlying liver disease due to hypothyroidism-induced myopathy, which increases urea production and decreases clearance through reduced glutamine synthetase activity. We present the case of a 60-year-old female who presented with markedly elevated thyroid stimulating hormone, reduced free thyroxine, and elevated serum ammonia levels. Although lactulose and rifaximin were initially started, her symptoms did not clinically improve until the underlying cause of her hyperammonemia was treated. Levothyroxine was initiated, and she reported rapid clinical improvement in her symptoms. Hyperammonemia carries a 40% mortality rate, and therefore clinicians need to be aware of this rare but intricate relationship between advanced liver disease and hypothyroidism for the prompt diagnosis and management of this condition.