Medical abbreviation:
LFT
Type:
Blood test
Definition:
Liver function tests assess liver, gall bladder and bile duct damage rather than function per se, the test usually includes the measurement of the following four chemicals:
Aspartate aminotransferase (AST): Is an enzyme found in both liver and heart cells. Levels of this enzyme are elevated whenever there is corresponding tissue damage.
Alanine aminotransferase (ALT): Is found in liver cells and levels are elevated when there is inflammation and damage to the liver.
Alkaline phosphatase (ALP): Is an enzyme found in the cells lining the bile ducts. When the bile ducts are damaged or blocked the levels of this enzyme are elevated and detectable in the bloodstream. The enzyme can also be found in bone and is therefore elevated in growing children and adults who suffer any form of bone damage.
Bilirubin: Is formed from the breakdown of haemoglobin, a chemical found in red blood cells. Bilirubin is handled by the liver and excreted in bile via the bile ducts. Levels are elevated in liver disease and diseases causing the increased destruction of red blood cells.
Gamma Glutamyl Transpeptidase (GGT): This test may also be included as part of the above set in some laboratories.
When would I need this test?
Liver function tests are often requested as part of a routine health screening, or when there are concerns of diseases that result in liver damage or failure, such as different forms of hepatitis (inflammation of the liver) and cancers. Liver function tests are also requested when there is suspected bile duct damage, caused by gallstones, autoimmune conditions or cancers. These conditions may present with some or all of the following symptoms, abdominal pain, jaundice, vomiting, diarrhoea, tiredness and weight loss. Liver function tests may also be monitored when taking particular medications, like statins and oral antifungal drugs or when an overdose of particular medications is taken.
