Decro; the thyroid energy from now food is a good supplement, just fill in with the salt and magnesium and the vitamins.
Your heartbeat thing is serious (this is not detox), in one case I had a similar reaction to iodine; or should I say; Iodine may give this reaction IF you are short of something, like in this case; salt;
A war veteran loaded with toxic stuff has been on Iodine for a while, experienced serious kidney and back pain; so serious he wanted to quit. At one occation while working out he lost his breath, arm got numb, nothing in the body seemed to work. He related it to the morning dose of iodine. So how can this happen. My theory is that his adrenals are shot (literally)
If you have adrenal fatigue like he has, a low aldosterone may cause a salt wasting (skin /sweat and kidneys) causing a steep drop in blood pressure= breathing problems, numbness, fainting.
After this incidence we had to start all over again with Iodine &co; this time with the required salt + more vitamin C and B ( needed big time by the adrenals.)
He found out that if he take enough salt he tolerate loads of lugols. If he dont do the salt he can only take a drop or two of iodine.
His kidney and back pain also went away as soon as he was enough salted.
" The adrenal glands produce many more hormones than just glucocorticoids. One very important hormone is aldosterone, a mineralocorticoid. Aldosterone regulates fluid and electrolytes (sodium, chloride, potassium and magnesium) in the blood, between and in the cells of the body. As adrenal fatigue progresses, the production of aldosterone lessens. This causes "salt-wasting". As the salt is excreted by the kidneys, water follows leading to electrolyte imbalance and dehydration. Those with adrenal fatigue should always add salt (preferably Sea Salt with its trace minerals) to their water. Soft drinks and electrolyte drinks like Gatorade are high in potassium and low in sodium, the opposite of what someone with low cortisol needs. Commercial electrolyte drinks are designed for those who produce high cortisol when exercising, not for someone who produces little or no extra cortisol during exercise. You need to add ¼ to 1 teaspoon of salt to a glass of water or eat something salty to maintain fluid/electrolyte balance." http://www.naturalnews.com/024985_cortisol_blood_adrenal_fatigue.html
I would adress the adrenals as well as the thyroid in your case; dont give up the iodine, but support yourself with other vit/minerals before you up the dose.