I can try to help clarify. I too have used Asacol. I used it for about 10 years. My colitis spread and got worse even though I was taking 8-12 pills a day. The enlightening part of that story was that overall I felt pretty good. Meaning there were times I didn't even feel like I had colitis and then there were times I had really bad bleeding, diarrhea, etc... During one of my good times (colitis was good) I had a colonscopy and biopsies taken. The pathology reported moderate and chronic inflammation. So, even though I felt good there was a lot of inflammation present. Second the bloodwork that you have taken for taking Imuran is just blood work to see if you have the enzyme necessary to metabolize Imuran. You may never have to take it but if you do you will know you can.
Bottom line, there can a hugh discrepancy between how one feels and what is actually going on a microscopic level. I am saying that is what is going on with you, but that may be what your doc is thinking. Have you gotten your path reports back? Or is this just your doc talking based on what he sees?
Based on your description I would be in no rush to go on Imuran. I however was in a totally different place. I had rampant inflammation in my colon and prednisone and Asacol weren't even touching it. Imuran got things in order for me.
Hope this helps.
MyUC