This is definitely due to your Imuran use. It's a well know fact that those taking Azathioprine or Imuran should consume a lot of water, half you weight in ounces over a course of a day. In the morning my urine is a bright yellow which is just a sign of the Imuran in my system. After a coffee and a few cups of water all is clear. This has nothing to do with any problem. You should definitely relax, take a deep breadth and enjoy your remission. I assume you are doing well. Do not call your doc over this, this is 100% normal.
39 Year Old Male, Dentist
Dx: Ulcerative Colitis 1996 via colonscopy and biopsy. Pancolitis with chronic and moderate inflammation.
Started UC around 92.
Past Meds: Asacol and occasionally Prednisone
Have had 6 colonscopies throughout my hx with UC.
Current Meds: Imuran, started with 200 mg and recently lowered it to 150 mg
Most recent colonscopy 2009 after 6 months of Imuran, colon is 90% healed
Currently in remission