Those are pretty high elevations of liver enzymes, but not exceedingly. People with one autoimmune disease (like Still's) tend to develop others, as well. I suppose there is really no way to know until further tests are done, including biopsy.
I have AIH. I don't know when my levels started to go up and I blew off most of the symptoms I had prior to having bloods looked at (after I became jaundiced)...so I can't answer that question. I had nausea, vomitting and really bad chills the week prior to going to the doc. It took 2 weeks with labs every other day to diagnose but confirmation of diagnosis was only after biopsy. Don't fear the biopsy, it sounds worse than it actually is. I had mine via the transjugular route as my prothrombin time was way off so I wasn't clotting. My ALT was 848, AST was 748 and bilirubin went from 9 (1st blood after jaundice) to 23.3 the day before starting pred and having biopsy. I have known others on the Yahoo group who have had their ALT/AST in the 1000's range. I really don't know what the correlation between level and damage is and it seems to differ with everyone. I had severe damage but no cirrhosis. I responded very well to treatment and am in remission and only on Imuran. I've been off pred for a year. I was diagnosed in Jan of '07.
This is a quick link to understand the differences between type I, II and III AIH. Also, look into Melissa Palmer's book. http://www.amazon.com/gp/product/B001BC8E0Y/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=0895299224&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1KHQ2WN0HMX35MMDE8E5
Lots of good info under the AIH section.
Let us know how it's going and what they say about the biopsy (you'll likely have the percutaneous one but I heard that one isn't so bad either).
Sorry if I made it sound bad...I'm actually pretty lucky. It was only super scary for a couple of weeks while they were trying to sort out what was wrong. I am lucky as I responded to treatment super quickly, granted I had sooooo many of the steroid side effects but they all go away when the dosage lowers, I don't have any fatigue or joint pain. There are some others who are on disability from their AIH as their fatigue, joint pain and/or increased affinity for acquiring flus seems higher. I think I have had one really bad cold since all this started...knock on wood as flu season is starting
Anyway, you can have fluctuating levels with mild AIH. They don't always treat mild AIH either. Do be sure you see a hepatologist if you can and not just a GI doc. Your rheumy sent you to a gastro but a hepatologist has extra training specifically in liver diseases.
Could the symptoms you are having be from the Still's? I was looking online about it and some of those are symptoms...