Elevated GGT test results - what further checkings are needed?

Hello,
A recent blood test indicated an elevated GGT level (77), while the other liver function tests were within normal range. Some past 15 years ago I had high transaminase levels (both SGOT and SGPT)for a period of at least 3 consecutive years. I never received any treatment or underwent any scans, as it was attributed me being overweight.

Other than a diagnosed prostatitus in 1988 (which was treated with medication), and a history of continuous gastro (reflux) problems, I am fine. I also take Tylenol on an average of once or twice a month for sinus headaches.

My question is: What does this elevated GGT test result indicate, and what further tests (for the liver, or otherwise) are recommended to do?

Thanks in advance,
Yal