I don't have thyroid problems but I came across your website while investigating isothiocyanates and goitrogens. I was interested in your information on potassium because many years ago I did a study in which potassium supplementation was used to eliminate symptoms of PMS.
I do not know if you know this but magnesium is the metal that is the coenzyme for the Na-K ATPase pump located on all cell membranes used to concentrate potassium inside of cells, where over 98% of the mineral is located. A magnesium deficiency in the presence of a potassium deficiency makes the potassium deficiency even worse. Replenishing just the magnesium will go some way into helping with the potassium deficiency because it will help concentrate it inside of the cell. Potassium supplements must be used to replenish a potassium deficiency because the acid-base balance that is usually messed up in a potassium deficiency must also be corrected in order for the body to retain the potassium. Using foods alone will not adequately correct a potassium deficiency. I never found any ratio that needed to be followed between the magnesium and potassium, just that both deficiencies needed to be corrected in the case of potassium deficiencies due to the role of magnesium in the Na-K ATPase pump. I did find however, that in order for the potassium to work on PMS (it took 3 months of daily potassium supplementation (600-1200 mgs/day) for the symptoms to go gradually away over this time) you could not touch phosphorous-free calcium or it was as if the potassium was not being replenished or working. Taking this form of calcium during this critical 3-month time would cause the complete return of symptoms and then you had to start the 3 month time period over. You could take dairy products, or any calcium naturally found in foods and this was fine. After the PMS is gone, taking phosphorus-free calcium was fine and symptoms did not return.
I did a hair analysis on myself throughout the time I was discovering this, about two years prior to the study I did, and it showed a very low potassium and a screeching high calcium. This was over 20 years ago but as I recall after correcting the potassium, my calcium values went down to normal. There is a study showing that use of calcium reduces PMS symptoms by 50%. Prior to discovering the potassium effects I had been on calcium and found this to be true. To me it was as if alot of PMS had to do with calcium balance, but that it could not occur in the presence of a potassium deficiency (whether due to the acid-base imbalance effecting the distribution of ionized/protein boiund calcium or some other reason I do not know). Correcting the potassium deficiency corrected the calcium imbalance.