Radiation in 1951 on Thyroid as a Baby

I was contacted by my mother while at college in the 70's and told that I needed to have my thyroid checked because my thymus gland had been radiated as an infant because it was enlarged. The radiation would have been in 1955 if a newborn, or in 1956, if during the first year of my life. When I saw the physician at the medical center on the campus where I was in school, my thyroid was palpated and, if I remember correctly, a scan was done . . . I was told that I had "scar tissue" on my thyroid and was started on synthroid to "keep my thyroid from functioning" so as to decrease the chance of developing thyroid cancer. I have been on synthroid/levothyroxin since that time and now am 62yo. Recently, I moved from the Raleigh, NC area where I had lived for 37 years to Winston Salem, NC. My primary care physician in Raleigh had kept me on the same dose of synthroid (125 mcg) as it had been originally prescribed when I was in college. I got a TSH and my thyroid palpated annually. When I started seeing a new primary in WS, I was told I needed to go to a specialist (endocrinologist) because the primary did not feel comfortable examining and prescribing my levothyroxin. I was told that my TSH was lower than it should be and my dose of levothyroxin needed decreased. I understood that it was not in the "normal" range, yet had not ever had a dose change from the 125 mcg I had taken for all the years since the thyroid scarring was first noted. If I remember correctly, the dose had always been kept at that level so as to "keep my thyroid from funtioning". The endocrinologist told me that there were "no studies" that showed the need to keep the thyroid from functioning and the risk to my heart and bones outweighed keeping the dose at 125 mcg as it had been for years. Of note, my heart function was without any issues and my bone density normal. Nevertheless, the new prescription was written for 112mcg. In my mind, i was thinking,why fix what was not broken ? However, I am the patient and not the doctor. Last week, I had another TSH done after 3 months on the reduced dosage of levothyroxin. An endocrinologist contacted me via their online portal to report that my level was still lower than where they wanted it to be and a further dose reduction would be prescribed when I come to my follow up appointment at the end of this week. Of note, the endocrinologist who contacted me was not the one I had initially seen and had reduced my dose to 112mcg. Also, of note, one week prior to getting my labwork, I was contacted and told that I would actually not see the initial physician, because they would be out of the office for 2 weeks and so would be seeing this other one who had sent me the message via the online portal. All this to say, I will have to tell my story once again to a third physician since arriving in WS (the primary, the initial endocrinologist,and now the new endocrinologist at my upcoming appointment). I admit that I am a bit anxious regarding the dose changes after all these years . . . I have never had any diagnosis of any cancers and very thankful for that! As for other medical history: I was diagnosed with rheumatoid arthritis in my early 40's, but that has been in remission for years as I have been on Enbrel. Because I have RA, I believe my immune system was not impacted by the radiation to my thymus  . . . and instead the RA is likely more genetic through my father. The only other diagnosis I have is a very stigmatized one (Bipolar 1), involving chemical imbalances within my brain . . . certainly one may believe perhaps that could have been influenced by the radiation as an infant . . . but again, I believe it to be also genetic as it also was a diagnosis of my uncle on my mother's side of the family. The bipolar, as well, is well managed with medication and has not been of any issue for many years, as I am compliant to both my medicinal and psychotherapy. I hope telling all this may be helpful in some way as it is my history as one of the many irradiated infants for thymus enlargement in the 1950's. I will continue to update my status after my appointment this week as well as going forward. for what it is worth as documentation.