I just had my first CT scan post-treatment (clear :)), and my blood work revealed my thyroids are hyperactive, resulting in my sudden weight loss and extreme insomnia. Ive seen a specialist, who said I either have Graves Disease or thyroiditis - I will be finding out which one soon. Either way, he says it is not related to my cancer/treatment, which I find hard to believe. I know hypothyroidism is a common long term side effect of radiation, but has anyone else experienced hyperthyroidism?