Where the test came from
In 1954–55 Arthur Karmen, Felix Wróblewski, and John LaDue at Sloan-Kettering found that transaminase activity spikes in the blood of patients with heart attacks and hepatitis. The insight—damaged cells spill their enzymes into the bloodstream—let doctors detect liver injury without a biopsy. The enzymes were later renamed from SGOT/SGPT to AST/ALT, and automated analyzers in the 1960s and '70s turned them into routine checkup items.
What each marker tells you
ALT lives mainly in the liver and is the most sensitive sign of liver-cell injury. AST is also found in heart and muscle, so a hard workout can bump it; an AST-to-ALT ratio above 2 hints at alcohol-related liver disease. GGT reacts to alcohol, drugs, and bile backup, while ALP and bilirubin point to blocked bile ducts from gallstones or jaundice. Albumin and prothrombin time reflect how well the liver makes proteins—key for staging cirrhosis.
If your numbers are high
In the U.S., the most common cause of mildly elevated enzymes is fatty liver disease (now called MASLD), followed by alcohol, medications and supplements, and viral hepatitis such as hepatitis B or C. Mild elevations that persist for six months warrant viral testing and an ultrasound. Weight loss, cutting back on drinking, and stopping unnecessary supplements often normalize them, but levels above 10 times normal or yellowing skin need prompt care.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Does a normal panel mean my liver is fine?
- Not always—advanced cirrhosis can show normal enzymes because few healthy cells remain.
- My AST went up after the gym. Is that bad?
- Muscle strain can raise AST and CK temporarily; retest after a few days of rest.
Sources reviewed: 2026-10-26
References
- Kwo, P. Y., Cohen, S. M., & Lim, J. K. (2017). ACG clinical guideline: Evaluation of abnormal liver chemistries. American Journal of Gastroenterology, 112(1), 18–35.
- Karmen, A., Wróblewski, F., & LaDue, J. S. (1955). Transaminase activity in human blood. Journal of Clinical Investigation, 34(1), 126–131.
- 대한간학회. (2023). 대사이상 지방간질환 진료 가이드라인.