Isolated GGT elevation. Range 80-170 for 6 month. All other liver labs normal. Normal ultrasound and normal doppler ultrasound. Could this be cirhosis?

No. Trust you're taking no meds that could cause this. About one person in 1000 has a genetic kink that causes lifetime elevated ggt. These folks are accused of being secret drunkards, and I have to write one or two letters a year to concerned employers, probation officers, etc. This is not "invisible cirrhosis" unless there's something you didn't share.