From the Guidelines
Elevated AST and ALT are blood test results that typically indicate liver damage or inflammation, and it is crucial to consult a healthcare provider to determine the underlying cause and appropriate treatment. In simple terms, these are enzymes normally found inside liver cells, and when the liver is injured or inflamed, these enzymes leak into the bloodstream, causing their levels to rise above normal [ 1 ]. Common causes include viral hepatitis, alcohol consumption, certain medications, fatty liver disease, and other conditions affecting the liver. The degree of elevation can provide clues about the type and severity of liver damage - mild elevations (less than 5 times normal) often suggest chronic conditions like fatty liver, while dramatic elevations (more than 10 times normal) typically indicate acute injury such as viral hepatitis or drug toxicity [ 1 ].
Some key points to consider:
- Elevated AST and ALT can indicate liver damage or inflammation
- The degree of elevation can provide clues about the type and severity of liver damage
- Common causes include viral hepatitis, alcohol consumption, certain medications, fatty liver disease, and other conditions affecting the liver
- It's essential to consult a healthcare provider to determine the underlying cause and appropriate treatment
It's also important to note that AST is also found in heart and muscle tissue, so elevated AST alone might indicate problems in those areas rather than the liver [ 1 ]. If you have elevated AST and ALT, you should consult with a healthcare provider who may recommend additional tests to determine the underlying cause and appropriate treatment [ 1 ].
In terms of the severity of abnormal aminotransferase, it can be classified as:
- Mild: <5 times the upper reference limit
- Moderate: 5 to 10 times the upper reference limit
- Severe: >10 times the upper reference limit [ 1 ]
Overall, elevated AST and ALT are significant indicators of liver damage or inflammation, and it is crucial to consult a healthcare provider to determine the underlying cause and appropriate treatment.
From the Research
Elevated AST and ALT: Understanding the Basics
Elevated AST (aspartate aminotransferase) and ALT (alanine aminotransferase) levels are commonly used biomarkers for liver damage 2. These enzymes are found in various tissues, including the liver, heart, and muscles. ALT is considered a more specific marker for liver damage, while AST is also present in other tissues.
Possible Causes of Elevated AST and ALT
The causes of elevated AST and ALT levels can be diverse, including:
- Liver disorders, such as chronic hepatitis, liver cirrhosis, and non-alcoholic steatohepatitis (NASH) 2, 3, 4
- Non-hepatic causes, such as polymyositis, acute muscle injury, acute myocardial infarction, and hypothyroidism 4
- Drug-induced liver injury, including acetaminophen toxicity 5
- Viral hepatitis, including hepatitis A and B 5
Interpreting AST and ALT Levels
The ratio of AST to ALT (AST/ALT) can provide clues about the underlying liver disease. A ratio greater than 2.0 is often associated with alcoholic liver disease, while a ratio less than 1.0 is commonly seen in chronic hepatitis and chronic cholestatic syndromes 3. However, this ratio may not be reliable in the presence of cirrhosis.
Next Steps
If elevated AST and ALT levels are detected, a complete medical history should be obtained, including risk factors for viral hepatitis, substance abuse, and other potential causes 4. Further investigations and referrals to a hepatologist may be necessary for suspected chronic viral hepatitis and liver cirrhosis. It is essential to interpret liver function tests correctly, considering not only the basic panel but also other biochemical parameters, such as albumin, INR, and platelet count 6.