Hi I am a 16 year old male and sometime in mid/ late July I went into the doctors and found out that I was hypothyroid. Anyway, I go in again, and my thyroid levels are normal, and have been ever since, but my thyroid gland is still enlarged. Now according to the doctors tests, I may have a re-activation of mono, could this be what is causing it?
Most causes of an enlarged thyroid are not worrisome. Even when the gland is enlarged, it could still be working properly. For people older than 65, it's possible that benign nodules on the thyroid cause enlargement. In your case, it seems possible that mononucleosis could be causing enlargement.