GGT

The GGT test is sometimes used to help detect liver disease and bile duct obstructions. It is usually ordered in conjunction with or as follow up to other liver tests such as ALT, AST, ALP, and bilirubin. Increased levels of GGT levels may indicate in general that the liver is being damaged but does not specifically point to a condition that may be causing the injury. While elevated GGT levels may be caused by liver disease, they may also be caused by alcohol consumption and/or other conditions, such as congestive heart failure.

GGT can be used to screen for chronic alcohol abuse (it will be elevated in about 75% of chronic drinkers). Sometimes it may be used to monitor for alcohol use and/or abuse in people who are receiving treatment for alcoholism or alcoholic hepatitis.

GGT may be ordered along with or as follow up to other liver function tests when a person has signs or symptoms that suggest liver disease. Some signs and symptoms of liver injury include:

• Weakness, fatigue
• Loss of appetitie
• Nausea and vomiting
• Abdominal swelling and/or pain
• Jaundice
• Dark urine, light colored stool
• Itching (pruritus)

GGT is increased in most diseases that cause acute damage to the liver or bile ducts but is usually not helpful in distinguishing between different causes of liver damage. For this reason, use of GGT is controversial, and guidelines published by the National Academy of Clinical Biochemistry and the American Association for the Study of Liver Diseases do not recommend routine use of GGT. These guidelines suggest that it can be useful in determining the cause of a high ALP.

GGT may be ordered when people with a history of alcohol abuse have completed alcohol treatment to monitor compliance with the treatment program.

If GGT is low or normal, then an increased ALP is more likely to be due to bone disease. A low or normal result would also indicate that it is unlikely that a person has liver disease or consumed any alcohol.

GGT levels may be elevated in heart failure. Some studies have shown that people with increased GGT levels have an elevated risk of dying from heart disease, but the reason for this association is not known.

Drugs that may cause an elevated GGT level include phenytoin, carbamazepine, and barbiturates such as phenobarbital. Use of many other prescription and non-prescription drugs, including nonsteroidal anti-inflammatory drugs (NSAIDs), lipid-lowering drugs, antibiotics, histamine blockers (used to treat excess stomach acid production), antifungal agents, antidepressants, and hormones such as testosterone can increase GGT levels.

Smoking can also increase GGT.

Levels of GGT increase with age in women, but not in men, and are always somewhat higher in men than in women.