I've been taking synthroid for several years due to radiation cau...

I've been taking synthroid for several years due to radiation caused thyroid damage. I appear to be quite sensitive to Synthroid. I get a total rush from a 77 mcg, but have no such effect when taking a 50 plus a 25. I've been told it is due to the dye in the 77. If my doses are too low (50 mcg), then I feel great for a week or two, but become foggy mentally and after a few weeks have sharp pains in the joints and muscles. At higher doses, I become irritable, have shortness of breath (77 mcg) and have burning sensations in the kidney area. I find that regular exercise (walking 1-2 miles/day) moderates these effects greatly and stabilizes the emotional swings. The amount of medication that I need to balance between these two extremes varies depending on the amount of exercise I get.