Aspartate aminotransferase (AsAT)

1. Aspartate aminotransferase (AST) is an intracellular enzyme that actively participates in amino acid metabolism. It is found mainly in tissues with a high level of metabolism: in liver cells (hepatocytes), myocardium (heart muscle), skeletal muscles, and also in smaller quantities in the kidneys and brain. Normally, the concentration of AST in the blood is low, but when the cells of these organs are damaged or destroyed, the enzyme is released into the bloodstream, which leads to an increase in its level.

Determination of AST level is an important component of the "liver profile" and cardiac markers. Most often, this analysis is used in combination with ALT for the diagnosis and monitoring of liver diseases (viral and toxic hepatitis, cirrhosis), as well as for assessing the condition of the myocardium in cardiac pathologies. Since AST is also contained in the heart muscle, its ratio with other enzymes helps the doctor differentiate the origin of damage.

Key indicators (what determines the test)

• Serum AST activity level (quantitative determination): A measurement of enzymatic activity (in U/L) that reflects the degree of damage to tissues rich in this enzyme.

• Coene-de-Ritis (AST/ALT ratio): An auxiliary calculation used for differential diagnosis of liver and heart diseases.

Preparation for the study To ensure maximum accuracy of blood test results, the following rules should be followed:

• Fasting: Blood is donated in the morning on an empty stomach (it is recommended to fast for 8–12 hours; drinking clean, non-carbonated water is allowed).

• Nutrition: The night before, you should avoid fatty, fried foods and alcohol.

• Physical and emotional state: One day before the study, avoid intense sports training, heavy physical exertion, and stress.

• Medications: Consult your doctor in advance about any medications you are taking (as some drugs, such as statins or antibiotics, can affect enzyme levels).

• Bad habits: Refrain from smoking at least 1–2 hours before donating blood.

Frequently Asked Questions (FAQ)

• Why can AST levels be elevated? An increase in AST is most often a sign of liver disease (viral or toxic hepatitis, fatty hepatosis, cirrhosis), but an increase is also possible with skeletal muscle damage, intense physical exertion, myocardial infarction, or trauma.

• What is the difference between AST and ALT? ALT is a more specific marker for the liver (since it is mainly found there), while AST is also present in large quantities in the heart muscle and skeletal muscle.

• When does a doctor order this test? The test is ordered when there is suspicion of liver or biliary tract disease, to monitor the intake of hepatotoxic medications, for routine preventive examinations, and as part of a comprehensive examination for pain in the right hypochondrium or general weakness.