From the Guidelines
Elevated AST and GGT levels are indicative of liver damage or disease, and prompt consultation with a healthcare provider is necessary for further evaluation and treatment. When both AST and GGT are high together, this strongly suggests liver problems such as alcoholic liver disease, viral hepatitis, non-alcoholic fatty liver disease, or medication-induced liver injury, as noted in the study published in the Journal of the American College of Radiology 1. The pattern and degree of elevation can help determine the specific cause - for example, AST levels more than twice as high as ALT (another liver enzyme) often suggest alcohol-related damage, as discussed in the study on alcoholic liver disease published in Hepatology 1. Some key points to consider include:
- AST is found in the liver, heart, and muscles, while GGT is primarily in the liver and bile ducts
- Alcohol consumption is a common cause of elevated GGT in particular
- The severity of abnormal aminotransferase can be classified as mild, moderate, or severe, with moderate and severe being discussed collectively due to significant clinical overlap, as outlined in the study published in the Journal of the American College of Radiology 1
- Treatment depends on the underlying cause and may involve lifestyle changes (reducing alcohol intake, weight loss), medication adjustments, or specific treatments for conditions like hepatitis. These enzymes serve as important biomarkers because the liver releases them into the bloodstream when liver cells are damaged, making them valuable early indicators of liver problems, as noted in the study published in the Journal of the American College of Radiology 1.
From the Research
Elevated AST and GGT Levels
- High levels of Aspartate Transaminase (AST) and Gamma Glutamyl Transferase (GGT) can indicate liver damage or disease 2.
- A study published in the Indian Journal of Clinical Biochemistry found that patients with Alcoholic Liver Disease (ALD) had higher AST/ALT ratios, GGT, and Alkaline Phosphatase (ALP) levels compared to those with Non-Alcoholic Steatohepatitis (NASH) and acute viral hepatitis 2.
- The same study suggested that a De Ritis ratio (AST/ALT) greater than 2 may indicate alcohol-induced hepatic mitochondrial injury and pyridoxine deficiency, while high GGT and ALP values may indicate enzyme induction by alcohol and mild cholestasis 2.
Possible Causes
- Elevated AST and GGT levels can be caused by various factors, including alcoholic liver disease, non-alcoholic fatty liver disease (NAFLD), and non-alcoholic steatohepatitis (NASH) 2, 3, 4, 5.
- A study published in the Journal of Gastroenterology and Hepatology found that vitamin E supplementation can improve biochemical and histological characteristics of NAFLD patients, including reducing liver enzyme levels 6.
Diagnostic Considerations
- The diagnosis of liver disease should be based on a combination of clinical examination, histology, serology, and biochemical parameters, including AST and GGT levels 2, 3.
- A study published in the Liver International journal found that there is no optimal ALT level to predict NASH and advanced fibrosis, and that metabolic risk factors should be evaluated to select patients for a liver biopsy 5.