Hi. having hyperthyroidism
are two different issues. Prostatomegaly is due to his age.
For hyperthyroidism which has been treated since so many years he should take radio-iodine
therapy. He will need one or two doses of it as he's suffering from the hyperthyroidism since more than a decade and as he has big sized thyroid. This therapy is safe and given at any nuclear medicine centre. Either your Endocrinologist
would refer him there or you can directly see the nuclear medicine specialist for the treatment.
Surgery is not required if the thyroid gets suppressed in one or two doses of radio-iodine therapy. But if his goitre- thyroid swelling- is too much then surgery will be the best option which will avoid future problems.