From the Guidelines
Elevated AST and ALT levels indicate liver inflammation or injury, and patients should consult a healthcare provider promptly for proper diagnosis and management, as the underlying cause can be effectively treated once identified. The most common causes of elevated aminotransferases are nonalcoholic fatty liver disease (NAFLD) and alcohol-induced liver disease, with NAFLD being the most common liver disease in first world countries, affecting 20% to 30% of the general population 1.
When evaluating patients with elevated AST and ALT, it is essential to consider the AST:ALT ratio, as a ratio greater than 2 is generally indicative of alcohol-induced fatty liver disease, while a ratio less than 1 is more suggestive of metabolic disease-related fatty liver 1. Other causes of elevated liver enzymes include viral hepatitis, certain medications, and autoimmune conditions.
Key steps in managing elevated liver enzymes include:
- Avoiding alcohol completely
- Reviewing all medications, including over-the-counter drugs and supplements, with a healthcare provider
- Maintaining a healthy diet low in processed foods and sugar
- Undergoing additional tests, such as a complete metabolic panel, hepatitis serologies, and possibly an ultrasound or other imaging of the liver, as ordered by a healthcare provider. Lifestyle modifications, including weight loss, exercise, and dietary changes, are often part of the treatment plan, regardless of the specific diagnosis, and can help improve liver function and overall health 1.
From the Research
Elevated AST and ALT: Causes and Evaluation
Elevated levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are commonly used biomarkers for liver damage 2. The causes of elevated AST and ALT levels can be varied, and a stepwise evaluation is often necessary to determine the underlying cause.
Common Causes of Elevated AST and ALT
- Nonalcoholic fatty liver disease (NAFLD) 3, 4
- Alcoholic liver disease 3, 4
- Medication-associated liver injury 3, 4
- Viral hepatitis (hepatitis B and C) 3, 4
- Hemochromatosis 3, 4
- Extrahepatic conditions such as thyroid disorders, celiac disease, hemolysis, and muscle disorders 4
Evaluation of Elevated AST and ALT
The evaluation of elevated AST and ALT levels should include:
- A fasting lipid profile 4
- Measurement of glucose, serum iron, and ferritin 4
- Total iron-binding capacity 4
- Hepatitis B surface antigen and hepatitis C virus antibody testing 4
- Ultrasonography 4
- Measurement of α(1)-antitrypsin and ceruloplasmin 4
- Serum protein electrophoresis 4
- Antinuclear antibody, smooth muscle antibody, and liver/kidney microsomal antibody type 1 testing 4
AST/ALT Ratio
The ratio of AST to ALT (AST/ALT) can be useful in determining the etiology of liver disease. A ratio of greater than 2.0 is often seen in alcoholic liver disease, while a ratio of less than 1.0 is often seen in chronic hepatitis and chronic cholestatic syndromes 5. However, the AST/ALT ratio can also be elevated in patients with cirrhosis, regardless of the underlying cause of liver disease 5.