I don't have Hashimoto's disease, but I do have GERD, hypothyroidism, and TMJ.  I have a lot of issues reaching higher notes due to mostly to tension from TMJ. I always have to make sure I am able to be standing and be able to move a bit to aleviate tension in order to be able to hit the higher notes atleast with a little less difficulty. I know that my hypothroidism and GERD effects my voice. I have to watch what I eat and make sure I am getting a good nights rest to ensure a good voice. I would suggest seeing a  Laryngologist or an ENT to answer your questions if you are having a major problem with higher notes.

I had Hashimoto's disease for 16 years before having my thyroid out for cancer - so I guess I can't really have Hashimoto's anymore :)  I had swelling of my thyroid gland that was obvious, but my thyroid was functioning in normal ranges, so I was difficult to diagnose.  In the years they were trying to diagnose Hashimotos I developed vocal nodules.  I personally believe that the swelling around my vocal chords was a contributing factor.  I was very keyed into the fact that my voice was acting differently and I was able to go through vocal rest and voice therapy to regain my voice.  My vocal chords are now nodule free and with my thyroid gone, it has helped my vocal stamina tremendously.  When going through the scope to check my nodules before surgery, the main concern was acid-reflux turning my vocal chords grey.  Seriously, when you have swelling of glands for a cold, it affects your voice - so why not the thyroid swelling affecting it as well?  My best wishes go to you - Hashimoto's is not fun!!

 

Lori