You can check in with your family doctor who can run some labs for you to check your thyroid. If he/she sees a problem they can refer you to an endocrinologist.
If you do have a thyroid issue, it could be related to UC but one never knows. I have two friends and many family members who have thyroid problems and have to take medication for it. It can pop up in anyone. I just recently went to see a hematologist since I am still anemic two years after my surgeries. He is checking my thyroid because he said anemia could be an indication of a thyroid issue which I didn't know. I haven't gotten the lab results back yet.
Hope that you don't have any issues but it never hurts to get it checked out. Good luck!