Alkaline phosphatase
It is an enzyme released as a response to injury to the bile ducts - not the liver itself. As more cells are injured, the more alk phos is released. Alk phos is not in itself harmful. Higher levels in the blood does not mean more tissue damage. Even lowering the alk phos does not necessarily lessen the risk. It is thought of as a marker in evaluating the disease process. It suggests what might be going on.
An example would be having a temperature is a 'marker' used to indicate that there may possibly be an infection going on somewhere.