What is Aspartate Aminotransferase?
Aspartate aminotransferase (AST) is an enzyme found in the liver, brain, lungs, pancreas, kidneys, and skeletal and cardiac muscle. AST levels measured in a blood test can indicate that tissues are injured or under metabolic stress.
A high AST relative to ALT is suggestive of alcohol-related liver disease. A lower ratio, where ALT is equal to or higher than AST, is more commonly associated with non-alcoholic fatty liver disease and other metabolic conditions.
Why Does AST Matter?
AST supports energy production and cellular repair. It plays a role in:
- Supporting metabolic balance by converting amino acids into compounds your body can use for fuel
- Promoting tissue and muscle repair through protein synthesis
- Helping your cells produce adenosine triphosphate (ATP), the body’s main source of energy
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How to Interpret AST
(Ranges may vary slightly by lab)
Standard reference ranges represent the middle 95% of healthy individuals but don’t necessarily reflect levels associated with longevity. Optimal ranges are derived from clinical guidelines, peer-reviewed research, and real-world outcomes data, with an emphasis on levels associated with peak functioning and reduced disease risk.
Benefits of Optimizing AST
AST is a marker of liver injury, not a therapeutic target itself. Treating the underlying cause of elevated AST may improve the following health outcomes:
- Improved liver health
- Better metabolic function
- Less organ stress and inflammation
- Lower risk of mortality1
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Low AST Levels
Low AST levels are typically not clinically significant. B6 deficiency can cause falsely low appearing AST levels on bloodwork.
Symptoms:
- Fatigue or weakness
- Jaundice
- Loss of appetite
Causes:
- Malnutrition
- Autoimmune diseases
- Kidney disease
- Dialysis
Healthspan impacts:
- Increased all-cause mortality risk in men2
High AST Levels
Because AST exists in multiple tissues, elevated levels may reflect liver injury, muscle damage, strenuous exercise, or broader cellular stress.
Symptoms:
- Fatigue and weakness
- Nausea and vomiting
- Loss of appetite
- Right-sided abdominal pain
- Yellowing of skin and eyes
- Dark urine
- Itching skin
Causes:
- Certain medications
- Viral hepatitis
- Liver damage or disease
- Pancreatitis
- Muscle injury (rhabdomyolysis)
Healthspan impacts:
How Hone Treats Out of Range AST
Your Hone physician will evaluate AST levels in a blood test alongside ALT and other liver function biomarkers. They’ll also consider your health history, overall health, and symptoms to determine a personal treatment plan.
- Medication adjustment*- if a medication is suspected to cause elevated levels
- Immunosuppressants* – to treat autoimmune hepatitis
- Antivirals* – to treat viral hepatitis
- Corticosteroids* – to reduce inflammation due to alcoholic hepatitis
*Your Hone Physician does not prescribe these treatments but will recommend further evaluation and help coordinate care with your primary care provider when medical treatment is indicated.
Ravel, V., et al. (2016). Association of aspartate aminotransferase with mortality in hemodialysis patients. Nephrology Dialysis Transplantation.
↑Clayton-Chubb D, et al. (2024). Serum Transaminases and Older Adults: Distribution and Associations With All-Cause Mortality. J Gerontol A Biol Sci Med Sci.
↑Han, J.H., et al. (2022). Markedly Elevated Aspartate Aminotransferase from Non-Hepatic Causes. Journal of Clinical Medicine.
↑Gallo, P., et al. (2021). Combined evaluation of aminotransferases improves risk stratification for overall and cause‑specific mortality in older patients. Aging Clinical and Experimental Research.
↑Hasan A, et al. (2024). Assessment of the Relationship Between Liver Enzymes and Cardiovascular Disease: A Study in Bangladeshi Adults. Endocrinol Diabetes Metab.
↑Noroozi Karimabad, M., et al (2022). Serum liver enzymes and diabetes from the Rafsanjan cohort study. BMC Endocr Disord.
↑Chee, N. M. Z., et al. (2024). Vitamin E improves serum markers and histology in adults with metabolic dysfunction-associated steatotic liver disease: Systematic review and meta-analysis. Journal of Gastroenterology and Hepatology.
↑Ebrahimzadeh, A., et al. (2025). Therapeutic effects of curcumin supplementation on liver enzymes of nonalcoholic fatty liver disease patients: A systematic review and meta-analysis of randomized clinical trials. Food Science & Nutrition.
↑Vargas-Pozada, E. E., et al. (2025). Coffee for the liver: A mechanistic approach. Biochemical Pharmacology.
↑Heath, R. D., et al. (2017). Coffee: The magical bean for liver diseases. World Journal of Hepatology.
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Reviewed for Accuracy by Our Medical Review Board
This biomarker information has been reviewed by a member of Hone’s medical review board. As part of the medical review team, physicians fact-check this content against the latest research and their own experience treating their patients.
Ashley Winter, M.D., is a board-certified urogynecologist trained at Weill Cornell and Cleveland Clinic. She specializes in female and male sexual dysfunction, urinary issues, genital pain, and hormone therapy.
James Staheli, D.O., is the Medical Director for Broad Health, Hone Health’s affiliated medical practice and a family medicine doctor in Atlanta, Georgia.
