Hi, my recent blood test indicates my GGT as 70 U/L, which is high. My alkaline phosphatase is 51 U/L, which is in the normal range, and my ALT is 17 U/L, AST is 23 U/L, Total Protein 68 G/L, Albumin 41 G/L & Globulin 41 G/L. What would be the likely cause of an elevated GGT?