AST
What this test measures
AST is an enzyme found in liver cells but also in muscle, heart and red blood cells. It leaks into the blood when any of those tissues are injured, so it is less specific to the liver than ALT. The test measures the enzyme's activity in a blood sample.
Why doctors request it
Many UK labs include it in the liver panel, and doctors compare it with ALT to help understand the pattern of a liver result. It is also raised by muscle injury, so it is sometimes read alongside creatine kinase.
What commonly pushes it up
- Fatty liver, alcohol and viral hepatitis
- Muscle injury, very hard exercise or a fall
- Many medicines, including statins and some antibiotics
- Heart muscle injury
- Cells breaking down in the sample tube (haemolysis)
- Thyroid conditions and coeliac disease
What commonly pushes it down
- Low vitamin B6
- Long-standing kidney disease
- Older age, by a small amount
Everyday reasons for a value outside the range
- Hard exercise in the previous few days raises it, sometimes more than ALT
- A haemolysed sample reads falsely high
- Not every lab includes it, so gaps in a timeline are common
About the sample
No fasting needed. Avoid hard exercise for two or three days beforehand. Read alongside ALT and creatine kinase.
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Read my report freeThis is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.