ASAT, Aspartate aminotransferase, is an enzyme that is found inside the cells of the liver, but also the heart, skeletal muscle and kidneys. ASAT plays an important role in the body's energy production by catalyzing the transfer of amino groups in certain metabolic processes. In cases of damage or diseases that affect these organs, ASAT can leak into the blood, making it an important marker when investigating various conditions, for example an inflamed or irritated liver.
What do elevated ASAT values mean?
P-ASAT is mainly used in combination with other liver values such as ALT (Alanine aminotransferase), ALP and GT, to assess the health of the liver and diagnose potential liver diseases. However, since ASAT also occurs in tissues other than the liver, elevated concentrations can indicate damage to the heart or muscles.
Elevated ASAT values are common and can occur without symptoms. Many times the elevation is temporary and is caused by factors such as medications, dietary supplements, alcohol or intense exercise. However, if the values remain high over time or are accompanied by other abnormal liver values, it may signal:
- Liver diseases: such as autoimmune hepatitis or cirrhosis.
- Infections: such as mononucleosis (glandular fever) or viral hepatitis.
- Heart problems: such as ischemic heart disease.
What is a normal AST value?
Normal reference ranges for AST vary depending on the laboratory, but a common range is approximately 0.25–0.75 µkat/L for adults.
p-ASAT high
Elevated levels of p-ASAT (plasma concentration of AST) may indicate liver damage, but since AST is found in several tissues – including the heart, skeletal muscles, kidneys and brain – an elevated value can also reflect conditions other than liver disease. A combination where AST is higher than ALT often raises suspicion of alcohol-related liver damage. Severely elevated AST can also be seen in myocardial infarction, muscle damage (for example after strenuous exercise or muscle diseases), hemolysis or acute pancreatitis. Therefore, it is important to interpret a high AST value in relation to other tests and the patient's clinical picture.
p-ASAT low
Low levels of p-ASAT are usually not clinically relevant and are generally considered normal. A low value means that there is no ongoing tissue damage in the organs where AST normally occurs. Very low levels can rarely be seen in severe liver failure where the liver's ability to produce enzymes is severely impaired, or in extremely low muscle mass. In practice, however, a low AST value is almost always considered a good sign that no acute damage is present.
How is AST interpreted in relation to other values?
ASAT values are often analyzed together with ALT. If both are elevated, it may indicate liver damage. However, an elevated AST value in relation to ALT may indicate heart or muscle damage rather than liver problems.
Do you have these symptoms? Then an AST test may be necessary
An AST test is relevant if there is suspicion of liver, heart or muscle damage. It is especially recommended if you experience symptoms such as:
- Persistent fatigue
- Yellowish skin or eyes (jaundice)
- Abdominal pain or swelling
- Dark urine
- Unexplained muscle pain or weakness
