I Am 48 Years Old Man. I Have Been Taking

I am 48 years old man. I have been taking Dilantin since 20 years old. I am taking 3 capsules ( 100 mg ) at bedtime daily. My ALT level is 29, AST level is 22 and Gamma GT level is 76 which is out of range. What should I take to lower the GGT level and what is it indicates regarding to my liver function. Your prompt advise would be much appreciated.