Welcome to the community! And congrats on your CAG! I grew-up with a CAG for a brother, he came to our family when I was 9 years-old, and he's now 32 and lives with my mom. They are wonderful parrots and so very intelligent, he will never cease to amaze you with the things he learns every single day...
I'm so glad that you took him for a Wellness-Exam, that's extremely important to do at least once a year, and it should include both a Fecal Culture and Microscopy and routine Blood-Work each year. A lot of people don't EVER take their parrots for wellness exams at all, often even bragging about how their birds haven't ever been to a Vet in 20 or 30 years because "They've never needed to go", and this is so wrong and such backwards thinking...So you're off to a great start...Is your Vet either a Certified Avian Vet or an Avian Specialist Vet? The reason I ask is that there is often a huge difference between a CAV or Avian Specialist and an "Exotics" Vet, especially in the US, where any general Vet can simply call themselves an "Exotics" Vet right after graduating from Vet School. They typically have very little to no education in Avian Medicine, nor training...
****It's not at all uncommon for pet/captive parrots of all species to show elevated Liver-enzymes in their Blood-Work, unfortunately it's extremely common in the US and I'd say is probably even the norm here. It's typically due entirely to their diet being extremely high in both FAT and SUGAR. A lot of people concentrate on cutting the fat out of their bird's diet, doing things like cutting out all of the fatty seeds, nuts, dried corn, etc. from their diet, but they totally forget about SUGAR content, which just gets turned into Fat in their bodies and stored in the Liver just like any other fat.A lot of people switch their parrots from a fatty seed-mix onto a "Fruit-flavored" pellet staple diet, and unfortunately most of the Fruit-flavored pellets contain so much sugar in them that they equate to as much or even more fat than the seed-mix had. So it's extremely important that any pellet diet is either a "Natural" pellet, or one of the few Fruit-flavored pellets that do not contain any added sugar, such as Tropican or Higgins In-Tune.
****Your CAG is only a year old, so the fact that his liver-enzymes are already elevated is extremely concerning to me. Typically such a young bird's Liver can actually compensate for the fatty or sugary diet and keep the enzymes down. So with an only 1 year-old Grey testing positive for high Liver Enzymes, it's going to be extremely important that you take this seriously and do everything you can to get them down, otherwise his life is going to be drastically shortened.
***If you could answer a few questions it will help us be better-able to help you and your Grey:
1.) He's 1 year-old, but how long have you owned him? At what age did you bring him home? And where did he come from, a private breeder, pet shop, etc.?
2.) What is his regular, daily diet? (either seed-mix or pellets, and exactly what brand and type of either, and then anything else such as what veggies, fruit, treats, people food, etc. does he eat each day) How long has he been eating this daily diet?
3.) Has he been at all sick since you've had him or prior to you having him (if you know), with anything such as any types of infections, any Avian Viruses, or any other illnesses or diseases? Has he ever been put on any medications or supplements, and if so, what for?
4.) Did you get a copy of his complete Blood-Work results? If so, can you post a photo of them for us to see, along with other results for any tests he had done, such as Fecal testing, X-Rays, etc.? If you didn't get a copy of his test results, you ALWAYS need to get a copy of them whenever he goes to a Vet, so you need to call the Vet anyway and have them email them to you, they should be able to just email you a digital copy of ALL his test results and findings, including any X-Rays, Ultrasounds, CT Scans, etc. It's your right to have them and you always want to keep a folder with all of his test results and findings just in-case you need them in the future...
***There are other reasons that Liver-enzymes can be elevated besides diet, even though 95% of the time it is totally and completely related to their diet. That's why I am asking about the rest of his Blood-Work results and his medical history...It's very unusual for an only 1 year-old bird to already have elevated Liver-enzymes, so it's possible that something else may also be at play in addition to his diet.
***What did the Vet say to you about his Liver-enzymes being elevated? Did he discuss this with you or give you any feedback or instructions on his diet, any supplementation or medications recommended, etc.?