Do you have your TSH, free T4 and free T3 results?
A great comment I found online....
"I have Hashimotos Thyroidis and very high TPO levels (>1300 10 months ago where the normal range was 59 ku/l). I have been taking 200g of Selenium per day, in addition l-thyroxin (but the smallest dose, as my TSH are sub clinical). I have also changed my life style quite a lot. Currently my TPO are 550 (normal range 101), so only 5 times higher than normal vs 20 times 10 months ago." >>> http://www.medhelp.org/posts/Thyroid-Disorders/High-TPO-Ab/show/1545417
I saw an improvement of 80 IU in six months (550 IU down to 470 IU) eating about 3 to 4 brazil nuts daily. Brazil nuts are high in selenium (50 to 90 mcg per nut depending on the soil). Studies show 200 mcg daily is used to help lower TPOAb levels
Compared to the results from another medhelp member, mine wasn't a drastic result but at the time I was eating a very bad diet, didn't exercise, had other deficiency states not to mention I had chronic inflammation from severe insulin resistance. 80 IU looked pretty good considering. :)
After all that, my TPOAb then skyrocketed during my year of hyperthyroidism; hyperthyroidism caused a lot of oxidative stress! Oxidative stress is when there isn't enough anti oxidants to combat free radicals (reactive oxygen species).
Here is some info from Medscape's article Selenium and the Thyroid Gland
Clin Endocrinol. 2013;78(2):155-164....
"Most authors attribute the effect of supplementation on the immune system to the regulation of the production of reactive oxygen species and their metabolites.
In patients with Hashimoto's disease and in pregnant women with anti-TPO antibodies, selenium supplementation decreases anti-thyroid antibody levels and improves the ultrasound structure of the thyroid gland. Although clinical applications still need to be defined for Hashimoto's disease, they are very interesting for pregnant women given that supplementation significantly decreases the percentage of postpartum thyroiditis and definitive hypothyroidism.
In Graves' disease, selenium supplementation results in euthyroidism being achieved more rapidly and appears to have a beneficial effect on mild inflammatory orbitopathy."