I believe that the elevated ALT value indicates your liver is inflamed. Do you drink alcohol? That could affect the number as could certain medications. What did your doctor said?
If you drink alcohol, take NSAIDS like Ibuprofin, or several other medications like some that treat UTI's...that could be why they are elevated. At one point, mine were over 700 and thankfully they are no under 100 (but are still high). If you do not drink and don't take any medications that could affect your liver enzymes then I would suggest looking at any other symptoms you may be experiencing. It could be a number of things.