Serum ghrelin is commonly known as glutathione, and is present in various tissue cells, with the highest levels in the liver, followed by cardiomyocytes, where the serum activity of the enzyme is low. When these tissues become diseased, with cell necrosis or increased permeability, the intracellular enzyme is released into the blood and the serum glutathione activity increases, mainly for the diagnosis of liver disease. The normal range is 5-40 U/L. Elevated serum ALT is commonly seen in various liver diseases, such as acute viral hepatitis, where the activity of ALT is significantly increased. Chronic viral hepatitis, alcoholic liver disease, drug-related hepatitis, fatty liver, and liver cancer will also have significantly increased glutathione activity. In addition, glutathione activity can be mildly increased by intrahepatic and extrahepatic biliary stasis.