AST (Aspartate Aminotransferase)

Blood

Comprehensive Metabolic Panel (CMP)

AST (aspartate aminotransferase) is an enzyme found in the liver as well as heart and skeletal muscle, so it reflects tissue injury from more than one source. A preventive practice reads AST alongside ALT to gauge liver health and to help interpret muscle or cardiac stress when it appears.

What It Measures

Liver and muscle enzyme; liver damage but also cardiac/muscle injury

Optimal vs. Lab Range

Longevity Optimal

10–26 U/L

Target range for optimal health and longevity based on research.

Standard Lab

10–40 U/L

Population-based reference range from standard labs.

Why It Matters

AST is a sensitive but less specific marker of tissue damage because it comes from several organs, which shapes how it is interpreted. Elevations can reflect liver disease, but also muscle injury, a cardiac event, hemolysis, or simply intense exercise in the days before testing. Comparing AST with the more liver-specific ALT, through the AST/ALT ratio, helps distinguish a liver process from a muscular or cardiac one and refines cardiovascular and metabolic risk assessment. A low AST is rarely significant, though it can occasionally hint at vitamin B6 deficiency.

When Low

Rarely significant when low; possible B6 deficiency

When High

Liver disease, muscle damage, heart attack, hemolysis, intense exercise

How to Optimize

Because AST rises from multiple tissues, improving it starts with identifying the source rather than treating the number in isolation. When the liver is involved, the same steps that support liver health apply: metabolic optimization, moderating alcohol, and reviewing potential drug effects. If recent strenuous exercise or muscle strain is the cause, allowing adequate recovery before retesting usually clarifies the picture, and a cardiac workup is pursued only when the clinical context warrants it. AST is most informative read with ALT and, where relevant, CK. Targets and treatment are individualized with your physician; this content is educational and not a substitute for medical advice.

Key Interventions & Linked Compounds

Strong evidence

Key Interventions

Liver support

exercise recovery

cardiac workup if indicated

Linked Compounds & Supplements

NAC

Milk thistle

Curated from clinical literature. Individual results vary; consult a qualified clinician before changing a protocol.

Ordering Notes

Specimen

Serum or plasma (venous draw)

Patient prep

No fasting required. Maintain usual diet and medications unless advised.

Recommended cadence

Annual

Reporting unit

Confirm with the performing lab — units vary by region.

Pre-analytic notes

Standardize draw time of day, hydration, and recent exercise. Note any acute illness, supplements, or hormonal therapies on the requisition.

Recommended Follow-Up Actions

1
Confirm the result is reliable
Repeat abnormal values before acting — preferably from the same lab, same time of day, and under consistent prep. Rule out acute illness, recent intense exercise, or medication effects that can shift AST (Aspartate Aminotransferase).
2
Compare against optimal, not just lab range
Use the optimal window above as the target. Lab "normal" is built from the general population and often misses early dysfunction.
3
Pair with related markers
Order a complementary panel covering metabolic, inflammatory, and hormonal context to interpret this marker properly.
4
Discuss interventions with a clinician
Use the interpretation guidance above to frame the conversation. Bring trends, not just one datapoint, to your visit.
5
Re-test on a defined cadence
If a change is implemented, re-measure in 8–12 weeks for fast-moving markers, or 3–6 months for slower ones, to confirm response before escalating.