Hello – The gentleman you spoke with is horribly misinformed, and could end up causing great harm to his nephew. Iodine is *not* the same as T3! In fact, there was a case in Houston recently where criminal charges were filed against a mother who stopped giving her son Synthroid and supposedly gave him seaweed instead (which is loaded with iodine):
(Note on links: if you click directly on the following link, you will need to use your browser’s “back” button to return to the boards after viewing, or you will have to log back in to the forum. As an alternative, you can right-click the link and open it in a new tab or new window).
To my knowledge, there aren’t any long-term effects of replacement hormone, as long as you remain on the correct dose for your body. The body’s need for replacement hormone does change as we age, so you will want to get follow up tests done at least annually once you find that “sweet spot” dosage. Staying on *too high* of a dose for your body can put you at increased risk for bone fractures.
As far as adding T3, that’s a decision that you and your doctor will need to make. Keep in mind that if you are making tweaks too quickly, that might make it more difficult in the long run to find the right regimen that will get you to feeling well again.
Take care!