ALT is glutathione, which is mainly in the cells, and is most abundant in the liver cells, where it is about 100 times more abundant in the whole liver than in the blood. In normal times, a small amount is usually released into the blood, so the serum does not contain a particularly high level of ALT. When it is abnormal, glutathione is released into the blood, which is what causes a significant increase in serum glutathione in the blood. Generally in viral hepatitis, drug-related toxic hepatocyte necrosis, a large amount of ALT is put into the human blood, so this index is an indicator to diagnose abnormal liver function. In case of hepatocyte necrosis, there is a significant increase in serum glutathione transaminase.