A case of hyperammonemia considered to be caused by hypokalemia without hepatic failure

Abstract

Hypokalemia increases ammonia production in the proximal tubules, which can exacerbate hyperammonemia in patients with hepatic encephalopathy. However, there are few reports of hyperammonemia due to hypokalemia in the absence of hepatic failure or a portosystemic shunt. Herein, we present the case of a 77-year-old patient with hypokalemia, hyperammonemia and impaired consciousness. The cause of hypokalemia was considered to be pseudohyperaldosteronism due to glycyrrhizin contained in shakuyakukanzoto. In this case, only fatty liver was present without cirrhosis, liver failure, or portosystemic shunt. No other causes for loss of consciousness were determined other than hyperammonemia. The impaired consciousness and hyperammonemia were improved with correction of the hypokalemia. The causes of hyperammonemia were considered to be the following: (1) the increased production of ammonia in the proximal tubule due to hypokalemia; (2) the increased transfer of ammonia into the blood due to alkalosis; (3) the decreased capacity for urea synthesis due to chronic hypokalemia; and (4) the decreased ammonia metabolism due to liver dysfunction associated with fatty liver. Therefore, hyperammonemia should be considered as a differential diagnosis in patients with hypokalemia and impaired consciousness regardless of the degree of liver dysfunction.