An elevated GGT level suggests that something is damaging the liver but does not indicate specifically what. In general, the higher the level, the greater the "insult" – or damage – to the liver. Elevated levels may be due to liver diseases, such as hepatitis or cirrhosis, but they may also be due to other conditions, such as congestive heart failure, diabetes, or pancreatitis. They may also be caused by alcohol abuse or use of drugs that are toxic to the liver.
A low or normal GGT test result indicates that it is unlikely that a person has liver disease or has consumed any alcohol.
A high GGT level can help rule out bone disease as the cause of an increased ALP level, but if GGT is low or normal, then an increased ALP is more likely due to bone disease.