From the Guidelines
Elevated GGT levels are associated with increased liver and all-cause mortality, and a raised GGT is a significant diagnostic indicator of underlying liver conditions requiring medical attention. Gamma-glutamyl transferase (GGT) is a liver enzyme that can be elevated in various conditions affecting the liver and biliary system. Normal GGT levels typically range from 8-61 units/L for men and 5-36 units/L for women, though reference ranges may vary between laboratories. Elevated GGT levels often indicate liver disease, biliary obstruction, alcohol consumption, or medication effects. Common causes include alcoholic liver disease, viral hepatitis, non-alcoholic fatty liver disease, bile duct obstruction, certain medications (like phenytoin, carbamazepine, and barbiturates), and pancreatic disease. GGT is particularly sensitive to alcohol use, making it a useful marker for alcohol-related liver damage or to monitor abstinence.
When GGT is elevated, further evaluation is typically needed, including additional liver function tests (ALT, AST, alkaline phosphatase, bilirubin), imaging studies, and possibly liver biopsy depending on the clinical context. According to the most recent study 1, the routine addition of GGT to a liver blood test panel increases the likelihood of an adult having abnormal liver blood tests, and a raised GGT is associated with increased liver as well as all-cause mortality. The highest quality study 1 also supports the use of GGT as a diagnostic indicator, as it found that the routine addition of GGT led to a marginal increase in sensitivity but at the cost of a loss of specificity and a higher false-positive rate.
Some key points to consider when evaluating GGT levels include:
- GGT is not specific to liver disease and can be elevated in other conditions, such as pancreatic disease or certain medications.
- The AST/ALT ratio can be useful in differentiating between alcoholic liver disease and other causes of liver disease, but it is not specific or sensitive 1.
- Carbohydrate deficient transferrin (CDT) may be measured to confirm critical alcohol consumption in patients who are suspected to deny or underreport intake, but it has limitations and confounding factors 1.
- The stage of liver disease can affect the measurement of CDT, and patients with cirrhosis may have a false negative result 1.
In terms of management, treatment focuses on addressing the underlying cause, such as alcohol cessation, medication adjustment, or management of liver or biliary disease. GGT elevation itself doesn't require specific treatment but serves as an important diagnostic indicator of underlying conditions requiring medical attention. Overall, the most appropriate course of action for elevated GGT levels is to conduct further evaluation and address the underlying cause, rather than treating the GGT elevation itself.
From the Research
GGT Lab Finding
- GGT (gamma-glutamyl transferase) is an enzyme found in many organs, including the liver, and is often used as a marker for liver disease 2, 3.
- Elevated GGT levels have been associated with various health conditions, including:
- Fatty liver disease: Studies have shown that frequently elevated GGT levels are associated with an increased risk of developing fatty liver disease 2.
- Chronic hepatitis C virus infection: Elevated GGT levels have been observed in patients with chronic hepatitis C virus infection, and may be an indirect marker of more advanced liver disease 3.
- Chronic heart failure: Elevated GGT levels have been associated with an increased risk of death or heart transplantation in patients with chronic heart failure 4.
- Digestive cancers: Repeatedly elevated GGT levels have been associated with an increased incidence of digestive cancers 5.
- Insulin resistance and intrahepatic lipids: Elevated GGT levels have been linked to reduced insulin sensitivity and increased intrahepatic lipids, which may contribute to the development of type 2 diabetes 6.
- The clinical significance of elevated GGT levels depends on the individual's overall health status and medical history, and should be interpreted in conjunction with other laboratory tests and clinical findings 2, 3, 4, 5, 6.