AST
The optimal range for AST (Aspartate Aminotransferase) is commonly cited as <25 U/L, tighter than the standard lab reference range of 8–48 U/L. Companion liver enzyme to ALT - also rises with muscle damage. AST/ALT ratio gives etiology hints.
How AST ranges relate
The standard lab range vs the optimization-focused target. Illustrative trajectory shows what a 12-week improvement pattern looks like — not real user data.
What AST Measures
AST is structurally related to ALT but found in more tissues (liver, heart, skeletal muscle, kidney, brain). Like ALT, it rises with hepatocyte damage but also rises with intense exercise (muscle release) - which can confuse interpretation in athletic users.
The AST/ALT ratio offers etiology hints: ratio >2 with elevation suggests alcohol or muscle origin; ratio <1 with elevation typically suggests viral hepatitis or NAFLD. In normal-range scenarios, the ratio is less informative.
What Affects This Biomarker
AST is influenced by: liver function, recent intense exercise (muscle release - can elevate AST 2–3× transiently), alcohol intake, muscle injury, statins (occasional rise), hemolysis (can falsely elevate), and most things that affect ALT.
In the Context of Peptide Protocols
Always interpret with ALT in context. If AST > ALT and the user trains intensely, repeat draw 3–5 days post-rest before assuming liver issue. On GLP-1s expect AST + ALT to fall together. On GH protocols, AST can rise transiently with intense training cycles - not a liver problem per se.
Peptides That Commonly Move AST
Frequently Asked Questions
What does AST measure?
AST is structurally related to ALT but found in more tissues (liver, heart, skeletal muscle, kidney, brain). Like ALT, it rises with hepatocyte damage but also rises with intense exercise (muscle release) - which can confuse interpretation in athletic users.
What is the optimal range for AST?
The optimal range for AST is commonly cited as <25 U/L. The standard lab reference range is 8–48 U/L.
What affects AST levels?
AST is influenced by: liver function, recent intense exercise (muscle release - can elevate AST 2–3× transiently), alcohol intake, muscle injury, statins (occasional rise), hemolysis (can falsely elevate), and most things that affect ALT.
Where This Fits in Your Panel
AST is one marker on a fuller panel. The Peptide Blood Work Checklist lays out the complete baseline panel, what to add by protocol type, and when to retest.
See the full blood work checklist →Upload any lab PDF and MyProtocolStack maps your values to AST and 40+ other biomarkers. StackAI interprets the trend in context of your protocol.
Start tracking →Last reviewed: June 2026
Informational only - not medical advice. Reference ranges vary by lab and individual context. Work with a licensed provider to interpret your specific results.