What is the significance of elevated Aspartate Aminotransferase (AST) at 47 units?

From the Guidelines

For an AST level of 47, the most appropriate initial step is to evaluate for hepatocellular injury and consider non-hepatic causes, given that AST levels can be elevated in various conditions beyond liver disease, including hemolysis, myopathy, thyroid disease, and exercise 1.

Clinical Considerations

When assessing a patient with an AST level of 47, it's crucial to consider the clinical context, including symptoms, medical history, and other laboratory findings. The differential diagnosis for elevated AST includes hepatocellular injury from various causes such as fatty liver disease, viral hepatitis, autoimmune hepatitis, and drug-induced liver injury, as well as non-hepatic causes.

Diagnostic Approach

• Hepatocellular Injury: If the clinical suspicion is high for hepatocellular injury, further evaluation may include testing for viral hepatitis, autoimmune markers, and considering a liver ultrasound to assess for fatty liver disease or other structural abnormalities.
• Non-Hepatic Causes: For patients with suspected non-hepatic causes of AST elevation, such as muscle injury or hemolysis, appropriate tests like creatine kinase for muscle damage or a complete blood count and reticulocyte count for hemolysis should be ordered.

Management

Management of elevated AST depends on the underlying cause. For example:

• Fatty Liver Disease: Lifestyle modifications including weight loss, exercise, and dietary changes are recommended. In some cases, medications like vitamin E or pioglitazone may be considered for non-alcoholic steatohepatitis (NASH) under the guidance of a hepatologist.
• Viral Hepatitis: Antiviral therapy may be indicated, depending on the type of hepatitis and the patient's condition.
• Autoimmune Hepatitis: Immunosuppressive therapy is typically required.

Monitoring and Follow-Up

Regular monitoring of liver enzymes and other relevant tests, along with clinical follow-up, is essential to assess the response to treatment and adjust the management plan as needed.

Given the complexity and the variety of potential causes for an AST of 47, a comprehensive clinical evaluation and targeted diagnostic testing are essential to guide appropriate management and improve patient outcomes 1.

From the Research

AST 47

• The AST (aspartate aminotransferase) level is an indicator of hepatobiliary disease, and elevated serum levels usually indicate hepatocellular damage 2.
• The ratio of AST to ALT (alanine aminotransferase) in serum can help differentiate between alcoholic and non-alcoholic liver diseases, with a higher ratio often indicating alcoholic liver disease 2, 3.
• AST is not liver-specific and can also be elevated in cases of muscle injury or disease, such as myocardial infarction or polymyositis 4, 5.
• Elevated AST levels can be associated with various liver conditions, including viral hepatitis, non-alcoholic steatohepatitis, and liver cirrhosis 2, 5, 6.
• The evaluation of abnormal liver chemistries, including AST, should involve a thorough history and physical examination, as well as further testing for viral hepatitis, autoimmune hepatitis, and other liver diseases 6.

Causes of Elevated AST

• Alcoholic liver disease 2, 3
• Viral hepatitis 2, 5, 6
• Non-alcoholic steatohepatitis (NASH) 5, 6
• Liver cirrhosis 2, 3, 6
• Muscle injury or disease (e.g. myocardial infarction, polymyositis) 4, 5

Evaluation and Management

• Obtain a complete history and physical examination 5, 6
• Order further testing, such as viral hepatitis panels and autoimmune hepatitis panels 6
• Consider referral to a hepatologist for further management 5, 6
• Monitor liver chemistries and adjust management plan as needed 6