Gamma-glutamyltransferase (GGT)
All liver diseases may show altered GGT serum levels.
GGT levels may be 2-3 times greater than the upper reference value in more than 50% of the patients with non-alcoholic fatty liver disease and above the upper reference value in about 30% of patients with chronic hepatitis C infection.
Raised GGT in patients with chronic liver disease is associated with bile duct damage and fibrosis. The lack of specificity but high sensitivity for liver disease makes GGT useful for identifying causes of altered ALP levels.[2]