Liver Function Tests (LFTs)

This refers to a set a blood tests which measures the level of enzymes found in the liver, which indicates functionality.

Aspartate aminotransferase (AST)

AST is found in tissues including liver, heart, muscle, kidney and brain.

It gets released into the serum when any one of these tissues is damaged.

Therefore, it is not a highly specific indicator of liver injury as elevation can occur because of other injured tissues. 

Alanine Aminotransferase (ALT)

This is an enzyme which is normally found in the liver hepatocytes and is released into the blood as the result of liver injury.

Thus, it serves as a specific indicator of liver status.

Alkaline Phosphatase (ALP)

Alkaline phosphatase is an enzyme found in high levels in bone and liver.

Smaller amounts of ALP are also found in the intestines and the placenta, so levels increase during pregnancy.

Its concentration in serum increases when the bile ducts are blocked.

But it is also affected by diseases which affect bones, e.g., Paget’s disease of bone and bony metastases from cancer.

Gamma glutamyltransferase (GGT)

This is found in the liver but not bone and so tells us if a raised ALP is from the liver.

Bilirubin

This is a product which is formed from the breakdown of haem. It is secreted by hepatocytes into the hepatic duct in the form of bile and helps to breakdown fats.

It is raised in hepatic dysfunction as well as haemolytic anaemia.

Pancreatic enzymes

Amylase

This is the most common enzyme which is assayed to measure pancreatic function.

It is released from the pancreas when the pancreas becomes inflamed.

Lipase

Lipase is another enzyme produced by the pancreas.

Lipase is considered more accurate for detecting pancreatitis, especially in pancreatitis related to alcohol abuse.

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