I am a 32 year old female (5'7", 160lbs) who is being treated for hypothyroidism and have been for the past 4 years or so. I am currently taking 175mcg Synthroid and my level seems to be in the normal range lately (My TSH levels started 4 years ago at over 50 and my most recent test was just over 2. I have learned that I feel/function best at just under 1, but since 1-3 is considered normal I didn't get a bump up in meds this last time). However, I have been experiencing other symptoms that have not been relieved with thyroid regulation. Most notably is my heart rate. My resting heart rate is regularly in the 90's and 100's throughout the day, and when I exercise (which I do often), I can EASILY get it into the 200's before I have to stop. I don't really feel exertion until it is in the 170's or 180's, and then I can only maintain that for 5-10 minutes at a time. I had an exercise stress test and an ECG done this year, and my doctor said everything looked normal - so he labled it inappropriate sinus tachycardia. However, it is keeping me from doing what I want to do as far as running distance events without having to walk. So, I want to learn to overcome the issue without having to take beta blockers. I can't help but think that the thyroid issue is related... perhaps there is an adrenal issue going on as well? I am an excessive sweater (ALWAYS sweating), have cold hands, often crave salty foods, but experience bad fluid retention if I eat too much salt. And, although I have been able to take off and keep off about 40 pounds since the thyroid diagnosis, I have about 25-30 more that I really should lose, and that is not an easy task either. I have to exercise daily AND keep my calorie range in the 1400-1600 range in order to see any progress, and even then it is slow. Are there other possibilities as to how all these symptoms might be interrelated and how I can go about changing my lifestyle to fix them?