ASAT is a liver enzyme that rises when liver cells are damaged, but also with muscle damage. So a high ASAT does not automatically mean a liver problem. The ratio with ALAT and your context, such as recent exercise, determine what the value really says.
Below you will read what ASAT measures, when an elevation is concerning, and what you can do about it.
What is ASAT?
ASAT (aspartate aminotransferase) is found in liver cells, but also in heart muscle, skeletal muscle and kidneys. That makes it less liver-specific than ALAT. Normal ASAT is below 35 U/L in men and below 30 U/L in women, though this differs per laboratory.
What does a high ASAT mean?
An elevation shows cells are being damaged somewhere: in the liver, muscles or heart. To determine the source, your doctor looks at the other liver values and at the ratio between ASAT and ALAT.
The ASAT/ALAT ratio: the most important compass
The ASAT/ALAT ratio is one of the most informative ratios in liver diagnostics (Botros & Sikaris, 2013):
- Below 1 - fits fatty liver or mild hepatitis.
- Above 2 - strongly suggests alcohol-related liver damage.
- Above 1 with known liver disease - may indicate fibrosis or cirrhosis.
A full explanation of all liver values is in understanding liver values.
Causes of a high ASAT
- Intense exercise - heavy strength training can raise ASAT for days due to muscle damage, not the liver (Pettersson et al., 2008).
- Fatty liver - often with a mildly elevated ALAT and ASAT (Younossi et al., 2016).
- Alcohol - especially when ASAT is clearly higher than ALAT.
- Medications - including statins and high doses of paracetamol.
- Heart or muscle conditions - because ASAT is also in those tissues.
What can you do about a high ASAT?
Mention recent intense exercise to your doctor; a repeat test after rest often shows whether muscles were the source. For a lifestyle cause, less alcohol, a healthy weight and exercise help. Never stop medications on your own, but discuss them. A check via the liver function test gives clarity together with a doctor.
Frequently asked questions
Can exercise raise my ASAT?
Yes. After heavy training, ASAT can stay elevated for days due to muscle damage. A measurement after a few days of rest gives a more reliable picture.
Is a high ASAT dangerous?
Not necessarily. A one-time, mild elevation is often temporary. It becomes more serious with repeated or large elevations, especially if ALAT or gamma-GT also deviate.
What is the difference between ASAT and ALAT?
ALAT is more liver-specific, ASAT is also in muscles and heart. That is why the ratio between the two is so useful for interpretation.
References
- Botros M, Sikaris KA. The de Ritis ratio: the test of time. Clinical Biochemist Reviews. 2013. PubMed
- Pettersson J, et al. Muscular exercise can cause highly pathological liver function tests in healthy men. British Journal of Clinical Pharmacology. 2008. PubMed
- Younossi ZM, et al. Global epidemiology of nonalcoholic fatty liver disease - meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology. 2016. PubMed
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