I get a hoarseness and persistent cough once in a while, but have never been able to ge an answer as to whether it is related to my Graves. Although every day I am finding out new symptoms that I didn't know about the day before!!
If you think you have thyroid disease, then it would be best to have a blloodtest to find out.
I also have not heard of a persistant cough as a thyroid sypmtom & I have read a lot on the subject through books & the internet
I have not read cough in thyroid. However, cough can be associated with nodules.
I assume you don't smoke, have allergies or anything else that might cause cough(?)