Gamma-Glutamyl Transferase (GGT)

Overview

Gamma-glutamyl transferase (GGT), also known as gamma-glutamyl transpeptidase, is an enzyme found throughout the body, with the highest concentrations in the liver. It plays a crucial role in the gamma-glutamyl cycle, facilitating the synthesis and degradation of glutathione, a potent antioxidant, and aiding in drug and xenobiotic detoxification^[1]. GGT is primarily tracked as a diagnostic marker for liver disease and alcohol consumption^[3].

Scientific Background

GGT catalyzes the transfer of gamma-glutamyl groups from molecules like glutathione to acceptors such as amino acids or water, forming glutamate^[1]. It is involved in the metabolism of glutathione and the detoxification of drugs. GGT is produced in the cell membranes of various tissues, including the liver, kidneys, and pancreas^[4]. Its activity is related to other liver enzymes like alkaline phosphatase (ALP), but GGT is more specific to liver and biliary diseases^[5].

Measurement and Testing

GGT is commonly measured in blood serum or plasma. Testing is typically recommended for diagnosing liver disease, monitoring alcohol use, or assessing bile duct blockages^[5]. Factors affecting results include alcohol consumption, certain medications, and liver conditions^[3].

Reference Ranges

Standard reference ranges for GGT vary by gender: typically 15–85 IU/L for men and 5–55 IU/L for women^[1]. Demographic variations exist, and results should be interpreted using laboratory-specific reference ranges. Elevated GGT levels often indicate liver or biliary disease^[2].

High Values

High GGT levels are associated with liver diseases such as hepatitis and cirrhosis, alcohol use disorder, and certain medications^[4]. Elevated GGT is also linked to increased risks of cardiovascular diseases and diabetes^[3]. Symptoms may include jaundice, fatigue, and abdominal pain^[5].

Low Values

Low GGT levels are less commonly a concern but may indicate reduced glutathione metabolism or certain nutritional deficiencies. However, GGT is not typically used to diagnose deficiencies^[1]. There are limited studies on the health implications of low GGT levels.

Improving Biomarker Levels

To improve GGT levels, lifestyle modifications such as reducing alcohol intake and maintaining a healthy diet are recommended^[5]. Certain supplements like antioxidants may support liver health, but their impact on GGT levels is not well-studied^[4].

Importance of Tracking

Monitoring GGT levels is crucial for diagnosing and managing liver diseases and alcohol use disorders. It helps differentiate liver from bone diseases when ALP levels are elevated^[5]. Regular tracking can aid in early detection and treatment of liver conditions.

Disclaimer

The information provided in this document is for educational purposes only and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.