Package No. 4.1.2 ‘Liver Function Tests’ is a screening test that covers basic parameters to assess the basic functions of the liver and biliary tract and identify potential abnormalities. Liver function tests are an important laboratory test for the initial assessment of liver function to detect cell damage, bile stasis, and the effects of alcohol and medications.
The liver performs hundreds of important functions every day: it participates in metabolism, detoxifies the body, aids digestion, and maintains normal bodily function. Liver function tests – ALT, AST, and GGT – enables the evaluation of health. This panel of tests allows for the detection of potential liver dysfunction even before the onset of significant symptoms. Liver function tests are useful for both a general assessment of liver function and for monitoring the effects of hepatotoxic drugs and clarifying the diagnosis of various liver and biliary tract diseases, ensuring timely detection of changes and the possibility of early intervention.
What does the ‘Liver function test’ include?
The panel includes key indicators – ALT, AST, and GGT. This is a basic liver function test that helps assess the functional state of the liver.
ALT (alanine aminotransferase) is one of the most important indicators of liver cell damage. If liver cell damage is present, ALT usually enters the bloodstream even before characteristic symptoms such as jaundice appear. For this reason, ALT enzyme activity is used as an indicator of liver damage caused by viral and autoimmune processes, drugs, and other toxic factors. Elevated ALT levels indicate liver cell damage and are a marker of inflammatory or toxic processes in the liver and biliary tract, often before jaundice or deterioration in health occurs.
AST (aspartate aminotransferase) is an enzyme found in liver, heart, and muscle cells. It maintains normal cellular function and energy production. When cells are damaged, such as in liver or heart disease, AST is released into the blood, and its levels increase. AST testing reveals the extent of tissue damage and, together with ALT, helps the physician more accurately assess the condition of the liver.
GGT (gamma-glutamyl transferase) is an enzyme found primarily in the liver and biliary tract. Its levels increase in the presence of liver and biliary diseases. It is particularly sensitive to bile stasis and the toxic effects of alcohol and certain medications.
What does it mean when liver function tests are elevated?
Elevated liver function tests (ALT, AST, GGT) are a laboratory signal that certain changes are occurring in the liver cells or biliary system. The liver has a high capacity for regeneration, but even minor or initial damage can manifest as elevated enzymes in the blood before symptoms occur.
Main possible causes of elevated liver function tests
- Liver cell (hepatocyte) damage
Elevated ALT and AST are most often associated with viral hepatitis, toxic exposure, the use of certain medications, or metabolic-associated steatotic liver disease (MASLD), a metabolic disorder. In such cases, ALT is usually elevated more significantly, indicating a liver-related cause of the changes.
- Bile Flow Obstruction
Elevated GGT may indicate bile stasis (cholestasis), which occurs with gallstones, inflammatory processes in the bile ducts, or functional disorders of bile flow.
- Alcohol stress on the liver
Regular or excessive alcohol consumption is often accompanied by elevated GGT and AST, sometimes with a characteristic predominance of AST over ALT.
- Other possible causes
Elevated AST can also be observed with muscle or heart damage, so the results are always evaluated comprehensively, along with other parameters and the clinical picture.
Elevated liver function tests are a reason for further evaluation, not a definitive diagnosis. To accurately interpret the results, the physician considers the level of elevation, the ratio of parameters, symptoms, and other test results. Early detection of changes helps prevent the development of more serious diseases and promptly initiate treatment or lifestyle changes.
Liver function tests: normal parameters
Liver function test values (ALT, AST, GGT) may vary slightly depending on the laboratory method, equipment, and reagents, so it is always important to refer to the reference values indicated on the results form. It should be noted that the normal range is assessed not only by individual parameters, but also by the combination of parameters. The doctor looks at the ALT/AST ratio, the level of elevation, and the overall clinical picture.
The test results enables the assessment of the functional state of the liver and biliary system, identifying possible signs of liver cell damage, bile stasis, or liver toxicity. The test also helps promptly identify potential liver dysfunction and monitor its condition over time.
