Normally thyroid originates under tongue and descends to the base of the neck. (Sometimes it can even descend into the chest cavity). So in your situation we could have atypically located thyroid. There are many causes for hypothyroidism including the broken feedback from blood to hypothalamus and then to pituitary which causes low TSH AND low T4
Thanks for your reply, 898_1. There seems little doubt that, as you said, my thyroid is atypically located as confirmed on the CT scan: an embryonic development anomaly. I didn't mention above that a FNA biopsy of my upper neck lump showed thyroid tissue and no evidence of cancer. Also my TSH was raised (over 20) and my T4 and T3 dropped below the reference range. It seems clear I have PRIMARY hypothyroidism. I've been asymptomatic since diagnosis 1/2 year ago. I am on 50 mcg Synthroid/day (recently increased from 25mcg/d ) and awaiting a followup thyroid function tests to monitor.
But I am curious to know why the Endo deemed this NOT to be Hashimoto's Disease? I understand that a small % (me included???) with Hashi's have a -ve anti-TPO and -TG antibody screen. There was no mention of Hashi's on the FNA report.
And the other answer I can't seem to get is whether atypically sited thyroids are any more prone to developing hypothyroidism (or cancer for that matter) compared to normal thyroids? I'm not sure any studies/research have been done into that?
All very confusing! :-(