Liver function tests are a type of blood test. A small amount of blood is taken from a vein in your arm. Liver function tests measure a series of chemicals which relate to the way the liver works. They include substances that are made in the liver or affected by the health of the liver cells, chemicals which are processed or excreted by the liver, and hormones that the liver makes in order to do its work.
This is a companion discussion topic for the original article at https://patient.info/digestive-health/abnormal-liver-function-tests-leaflet