Liver
AST
What This Marker Tells Us
An enzyme found in liver, heart, muscle, and other tissues that leaks into blood when cells are damaged.
Why It Matters
Elevated AST indicates liver damage, heart muscle damage, or muscle injury from exercise or disease. Because AST exists in multiple tissues, it's less specific for liver than ALT. However, the AST/ALT ratio (De Ritis ratio) helps identify the type of liver disease. AST also rises with intense exercise and muscle damage. Monitoring AST helps detect liver injury from medications, supplements, alcohol, or disease before symptoms appear.
How to Interpret Your Trends
Low AST is generally not concerning. Typical AST (10-40 U/L) indicates healthy liver and muscle tissue. Mildly elevated AST (41-100 U/L) may reflect intense exercise, muscle injury, or early liver stress. Moderately elevated AST (101-300 U/L) suggests liver disease, heart damage, or significant muscle breakdown. High AST (above 300 U/L) indicates severe liver injury, heart attack, or rhabdomyolysis requiring immediate medical attention.
What Influences This Marker
Intense exercise, particularly resistance training, temporarily raises AST through muscle microtrauma. Alcohol, medications, supplements, and toxins damage liver cells, elevating AST. Viral hepatitis, fatty liver disease, and cirrhosis chronically elevate AST. Heart attacks and muscle diseases increase AST. Timing labs away from intense training, moderate alcohol intake, and liver health maintain normal levels.
How Your Team Uses It
Your coach uses AST with ALT to assess liver health and distinguish liver injury from exercise-related muscle damage. Elevated AST prompts investigation of training intensity, supplement use, alcohol intake, and liver disease. The AST/ALT ratio guides diagnosis when liver enzymes are elevated.
Related Signals We Also Review
ALT, AST/ALT ratio, GGT, alkaline phosphatase, bilirubin, CK if available, training load, and supplement use complete the AST interpretation.