We are in the same situation as you, with our daughter. I have not found anything online that has been helpful. Last week we did the biopsy and it actually came back normal. We have an appointment with the GI doctor early January 09 to go over things. Good luck.
My 4 1/2 month old has had the same!!! We have had test after test and no answer. His last AST was 107 & ALT 96. He nurses well and is growing great, but they continue to rise. I'm frustrated...We see a liver specialist & even he is baffled!
You might want to talk to a doctor about ultrasound therapy and also consider doing some imaging test to rule out any serious causes. Hepatitis or mononucleosis would probably have shown in the blood tests but you can ask for another blood test and be sure to mention you want to rule out hepatitis and mononucleosis.
We are experiencing the same problem with our 5 month old son. We went to the hospital on Tuesday to have blood tests done and also an ultrasound on his liver. The ultrasound results came back normal, they showed nothing abnormal but some of the bloodwork that has already come back is still showing elevated levels of enzymes and the doctor is really not sure why. She told me she consulted with a Gastroenterologist and that she was going to call me back as soon as she showed my son's test results to the doctor. I was starting to feel a bit better, since the doctor doesn't seem to think it is anything major but looking at everyone else's comments on here, it looks like the next step may be a liver biopsy and that really freaks me out! My son seems completely fine, he is healthy and happy, he weighs 20 lbs (8lbs 11oz at birth), he obviously eats very well, I really don't know why this is happening to him.