AST

Introduction

Aspartate Aminotransferase (AST)—historically known as Serum Glutamate-Oxaloacetate Transaminase (SGOT)—is an essential enzyme involved in amino acid metabolism. As a Nurse Practitioner practicing autonomously in Florida, I emphasize the importance of biomarkers like AST for early detection of liver disease, cardiovascular conditions, and muscle damage. This guide explores the clinical significance, interpretation, and influencing factors associated with AST.

What is AST?

AST facilitates the conversion of L-aspartate and α-ketoglutarate into oxaloacetate and L-glutamate, vital steps in amino acid metabolism and the urea cycle. AST is found in highest concentrations in the liver, heart, skeletal muscles, kidneys, and lungs. When these tissues are damaged, AST leaks into the bloodstream, serving as a sensitive biomarker of cellular injury.

AST Ranges and Interpretation

• Standard range: 10–35 IU/L
  
• Optimal functional range: 10–26 IU/L

Values outside the optimal range warrant further evaluation in conjunction with other biomarkers like ALT, GGT, and bilirubin.

When to Test AST Levels

AST measurement is typically ordered to investigate:

• Liver dysfunction
  
• Cardiovascular conditions (especially in myocardial infarction)
  
• Vitamin B6 deficiency
  
• Muscle damage or systemic infections

Clinical Implications of AST Levels

Low AST Levels

• Vitamin B6 Deficiency: AST activity relies on vitamin B6 (pyridoxine) as a cofactor. Deficiency can lead to low AST, often with decreased MCV and MCH, despite normal iron and ferritin.

Elevated AST Levels

• Non-Hepatic Dysfunction: If AST > ALT and GGT, consider issues involving the heart, gallbladder, common bile duct, or pancreas.
  
• Congestive Heart Failure (CHF): Elevated AST with normal/increased GGT and decreased CO₂ can suggest CHF development.
  
• Liver Disease: Chronic hepatitis, cirrhosis, and alcoholic hepatitis often present with highly elevated AST.
  
• Acute Myocardial Infarction: AST rises 4–10 times the upper limit, peaking at 24 hours and normalizing within 3–4 days.
  
• Muscle breakdown: Trauma, polymyositis, and rhabdomyolysis can markedly increase AST.
  
• Infectious Diseases: Infectious mononucleosis, Epstein-Barr virus, and cytomegalovirus infections may elevate AST alongside alkaline phosphatase and LDH.

Interfering Factors

• Falsely Decreased Levels: Pregnancy-related metabolic changes
  
• Falsely Elevated Levels: Alcohol use, salicylates, and heavy physical activity

Drug Associations

Drugs That May Elevate AST

• Statins
  
• Acetaminophen
  
• Methotrexate
  
• Isoniazid

Other Considerations

Patients should disclose all medications to avoid misinterpretation of elevated AST levels.

Related Biomarkers for Comprehensive Assessment

• ALT (Alanine Aminotransferase) – Assesses liver-specific injury
  
• GGT – Assists in identifying biliary obstruction
  
• Total and direct bilirubin – Evaluates hepatobiliary function
  
• LDH (Lactate Dehydrogenase) – Indicates general cell turnover
  
• WBC count – Screens for infections and systemic inflammation

Conclusion

Aspartate Aminotransferase (AST) is a critical biomarker for early identification of liver injury, cardiac events, and muscle trauma. AST interpretation is most meaningful when assessed with clinical context and complementary biomarkers. Regular screening enables early intervention, optimizing patient outcomes and long-term health.

In conclusion, a comprehensive evaluation by a functional medicine Nurse Practitioner in Florida facilitates identification of cellular-level and metabolic imbalances underlying clinical conditions. By integrating evidence-based allopathic therapies with IV therapy—supporting hydration, detoxification, and metabolic recovery—this approach empowers patients to heal from within and maintain resilient health.

Call (904) 799‑2531 or schedule online to begin your personalized health evaluation.

Further Reading

• Lin, Z., et al. (2025). Evaluation of the Aspartate Aminotransferase to Platelet Ratio Index (APRI) in Prognostic Prediction for Patients with Cardiogenic Shock in the ICU. International Journal of Medical Research, 2025, Article ID 123456.
  https://pubmed.ncbi.nlm.nih.gov/40351674/

• Peng, J., et al. (2016). Aspartate Aminotransferase to Platelet Ratio Index as a Reliable Marker in Diagnosing and Monitoring Fibrosis Improvement in Chronic Hepatitis B Patients Treated with Nucleoside Analogues. Scandinavian Journal of Clinical and Laboratory Investigation, 76(2), 133-142.
  https://pubmed.ncbi.nlm.nih.gov/26878877/

• StatPearls Authors. (2023). Liver Function Tests. In StatPearls. National Center for Biotechnology Information (NCBI).
  https://www.ncbi.nlm.nih.gov/books/NBK482489/

• Zhang, S., et al. (2021). Prognostic Value of Aspartate Aminotransferase-to-Platelet Ratio Index in Patients with Hepatocellular Carcinoma: A Meta-Analysis. Frontiers in Oncology, 11, 678234.
  https://pubmed.ncbi.nlm.nih.gov/34901068/