A GGT test is most often used to: Help diagnose diagnose Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which disease or condition explains a person's symptoms and signs. It is most often referred to as a diagnosis with the medical context being implicit. https://en.wikipedia.org › wiki › Medical_diagnosis Medical diagnosis - Wikipedia liver disease . Figure out if liver damage is due to liver disease or a bone disorder. Check for blockages in the bile ducts.