Fasting is required for blood tests for transaminases because blood specimens after a meal are prone to celiac disease, which can affect the results of transaminases. Elevated transaminases generally indicate liver damage, but causes other than liver damage can also cause elevated transaminases, as they are very sensitive and many factors can cause normal transaminase values to fluctuate up and down. In healthy people, transaminase measurements may be different at different times of the day. When liver cells are damaged by inflammation, necrosis, or poisoning, transaminases are released into the bloodstream, causing an increase in serum transaminases. Usually the main aminotransferase enzyme checked in the physical examination is glutathione, and 1% of liver cell damage can double the concentration of aminotransferase ALT, so the level of glutathione can be more sensitive to monitor whether the liver is damaged.