What can an AST test tell you?
The AST test is commonly used to:
Evaluate liver health. Elevated AST levels can indicate hepatitis, alcohol-related liver disease, nonalcoholic fatty liver disease, or cirrhosis.
Assess muscle injury or inflammation. High AST may occur in rhabdomyolysis, polymyositis, or after strenuous exercise.
Monitor treatment progress. AST trends help evaluate recovery from liver injury or response to medications affecting the liver.
What is being tested?
Aspartate aminotransferase, or AST, is an enzyme that helps metabolize amino acids. It is abundant in the liver’s mitochondria but also found in other tissues. When the cells in these tissues are damaged by inflammation, infection, toxins, or injury, AST enters the bloodstream.
Because AST exists in multiple organs, isolated elevation can come from non-liver sources, such as:
Muscle damage (exercise, trauma, myopathy)
Heart disease (heart attack, myocarditis)
Kidney injury
This is why providers often evaluate AST in the context of ALT, creatine kinase (CK), and cardiac troponin to identify the organ of origin.
Where is the AST test typically included?
The AST test is typically included in the following panels:
Liver function test (LFT), which measures liver enzymes, bilirubin, and albumin to assess liver health
Comprehensive metabolic panel (CMP), which is a broader assessment of metabolic health
Muscle or cardiac panels, which measure other biomarkers to identify non-liver injury
Who should get an AST test?
Your provider may recommend an AST test if you have symptoms or risk factors of liver, muscle, or heart conditions, such as:
Fatigue or weakness
Abdominal pain or swelling
Jaundice (yellowing of the skin or eyes)
Unexplained muscle pain or tenderness
Dark urine or pale stools
History of alcohol use, hepatitis, or high cholesterol
It is also recommended for people taking medications that can affect liver function (e.g., statins, acetaminophen, certain antibiotics).
