Good morning! A TSH level of .35 indicates to me that you should discuss this with your doctor and speak about medication level. That is a very low TSH level with normals going up to 4.0 and most organizations recommending a level of 2.5. I am not certain you need more iodine right now, you need to have your cough checked out relative to your very low TSH level and include any other symptoms (weight loss, etc.). A low TSH such as you have and the high dose of medication that you are on would cause me to recommend, if you were my patient, further labwork and/or a medication adjustment. The voice changes have me very concerned. Foods high in iodine include seafood, iodized salt, eggs,cranberries,legumes. The daily requirement is about 150 micrograms/day; the RDI is 95 micrograms per day - so somewhere between 95-150 mcg per day is needed. Goitrogens, or foods that interfere with thyroid function include cabbage, turnips, rapeseeds, peanuts, cassava and soybean/soy milk soy anything. A tolerable upper limit is 1100mcg/day (upper limit). Iodine is needed to make T4 an inactive hormone that needs selenium to activate itself into T3. The thyroid is a complicated energy regulator. Generally if iodine is low you would see a high TSH and you have an almost non-existant level. Generalities only. Important for stable TSH levels. Take your Thyroid medication on an empty stomach about .5 hours before food. In summary, I have listed the best sources of iodine containing foods and foods that will interfere with the proper functioning of the thyroid, how to take your medication for stable thyroid function, caution to see physician for medication re-evaluation based on TSH of .38, throat problems, changes in voice and seek guidance from the doctor before adding any supplements. Thank you for seeking input from HCM. Kathryn Shattler, MS,RD