Interpreting abnormal liver function tests

Liver function tests (LFTs) are a panel of laboratory results that can be helpful in diagnosing and assessing the extent of liver disease. Although they are often requested, abnormal results are often inadequately investigated.1 Doctors can be poor at determining the most common aetiology behind the abnormalities.2

Despite the name, most of the components of LFTs do not directly measure liver function. Four of the components of LFTs are enzymes that are normally found inside the cells of the liver (hepatocytes or biliary cells) but that can “leak” into the blood after liver or biliary injury. Measuring the level of these enzymes in the serum will not determine the degree of liver function but can reflect the extent and mode of liver injury. The remaining two components of LFTs are substances that are produced or processed/excreted by the liver. These latter components are therefore a better measure of the level