A liver function test is a blood test used to determine any disease, damage or impact on the liver. The health of the hepatic, or liver, system is reflected in this panel of tests that include clotting abilities, liver enzymes and bilirubin levels, according to MayoClinic.com. Typically, results of the test fall within a standard range of normal limits and do not need further interpretation. However, there are a multitude of clinical reasons why liver functions may be elevated.
Alcohol and Toxins
The two enzymes that reflect liver health are alanine aminotransferase, or ALT, and aspartate aminotransferase, or AST. When elevated, these enzymes show damage to the actual liver itself. All chemical substances are cleaned from the bloodstream via the liver, including alcohol and ingested toxins. Chronic alcoholism can damage the liver's ability to function, and toxin or heavy metal ingestion will immediately impact the liver. In the case of acetaminophen overdose, these enzymes are checked immediately to assess the degree of incurred liver damage.
Liver Disease
Diseases of the liver, including cancer, hepatitis and cirrhosis, will elevate readings from a liver function test. The liver removes ammonia from waste products such as urine. Increased ammonia levels will show on a liver function test and represent a disease of the liver, reflecting that the liver is not just damaged, but is also unable to complete a primary function. Elevated AST levels will show up prior to any physical symptoms, such as jaundice, that are indicative of liver disease.
Hepatobiliary Problems
The hepatic system is a part of the human digestive system, allowing for the breakdown, absorption and processing of ingested nutrients. Any diseases or disruptions within the digestive system could potentially impact liver function tests. Commonly, diseases of the gallbladder, such as cholecystitis, will show up with increased bilirubin and AST levels. Obstructions due to strictures or gallstones will also reflect in liver functions with a drastic increase in bilirubin.
References
- American Academy of Family Physicians: Special Considerations in Interpreting Liver Function Tests
- Mayo Clinic: Liver Function Tests---Results
- "QJM: An International Journal of Medicine": Contrasting Liver Function Test Patterns in Obstructive Jaundice Due to Biliary Structures and Stones
- Health on the Net Foundation: Hepatitis B
