If you have not already done this, it could be well worth your while researching your family tree. It would enable you to obtain death certificates for your past relatives that could perhaps provide hard evidence of thyroid disease, or any other disorder, that runs in your family. You would have to pay for the certificates but you never know, it could prove to be a worthwhile investment!
Family History: If you have not already done this... - Thyroid UK
Family History
Except that a birth certificate will never say 'cause of death - hypothyroidism'. I have most of my families death certificates, and, whilst I'm pretty sure most of them were hypo, you wouldn't know it from the 'cause of death'.
You never know, you might see 'myxoedema' which is the end point of long untreated thyroid disease. Someone I know claims to have seen 'hypothyroidism' on death certificates she obtained, as well as other conditions she suffers from. That's what gave me the idea for this post. It's just that whenever you are asked if there is any history of this or the other condition in your family, nine times out of ten you probably won't know for sure unless you actually asked your more senior relatives whilst you still could, or did this kind of research.
Tend to agree with GG. being wrongly treated can cause other problems that could cause in time your cause of death or have contributed to it.
Most of mine in the 1800's died of bronchitis usually with something else such as senile decay or in the case of a forty year old woman " exhaustion" ,probably after a football team plus reservs of children..Old age was one I liked. Of course diagnosis of causes was not very developed one cert added "no post mortem" . None mentioned thyroid.