My hashimotos may be due to low-selenium diet.doc prescribed me lt4.can i increase se in my diet and also take the lt4? or would that lower tsh 2 much

Yes and NO: Yes, you can increase Selenium in your diet if you have been diagnosed with a significant deficiency. If the deficiency afects thyroid function, an exceedingly rare situation, then replacement therapy will restore no more than normal thyroid function. see :http://www.medscape.com/viewarticle/777483_5 regarding thyroid antibodies and selenium, a more complex matter entirely.