From my research some say selenium is great others say it does nothing.
This is a cut and paste of what Dr Lupo said on the Thyroid Forum back in Nov 2005
Selenium at 200mcg per day is being looked at to improve immune system thyroid disease such as Hashi and Graves. There are limited data regarding long term use. Use the amino acid form (selenomethionine or selenocysteine) and not the salt form. Over 1000mcg/day may be toxic.
This is what Mary Shomon said on her site
Greek researchers studied the impact of selenium treatment on antithyroid peroxidase (TPO) levels in patients with Hashimoto's thyroiditis. In the study, patients received 200 mcg of selenium (an l-selenomethionine supplement) orally for 6 months. Half the group continued taking selenium for an additional six months, and the other half stopped selenium supplementation. The researchers found that the anti-TPO levels were reduced substantially during the first six months, with an approximately 5.6% reduction after 3 months, 9.9% after six months, and an additional 8% in the additional six months for the groups that continued with supplementation. The group that stopped supplementation saw a 4.8% increase in the antibody levels during the second six months.
So basically give it a go and see how you feel in 6 months.
Personally for me it hasn't worked but it may well do for you.
People here told me to take selenium and Dr. Lupo agrees with it, it helps some people, in September I will know. The dose is 200 mcg (= to 200 micrograms) a day.