Liver health

ALT and AST are enzymes held inside liver cells. ALP comes from the cells lining the bile ducts, the channels that drain bile out of the liver. Albumin is the main protein the liver makes. Globulin is mostly antibodies, and total protein is the two added together. Bilirubin is a pigment left over when old red blood cells are broken down, and the liver clears it out of the blood.

The liver clears waste out of the blood and makes the protein that holds fluid inside blood vessels, and it carries on doing both while it is being damaged. So there is usually nothing to feel, and a blood test is how damage gets picked up. ALT and AST belong inside liver cells, so finding them in the blood means cells have been injured, by alcohol or by fat gathering in the liver.