I agree with these posts and esp. with Missy when she says to drink water. There are a lot of illnesses that can be relieved by drinking lots of water. As far as the thyroid/ adrenal question goes, often problems with both go hand in hand. My dad was hypothyroid and was extremely thin. I am hypo, but did go through times of extremely fast heartbeat. The problem there was that I was low on magnesium It didn't show on the test, but the test showed a slight deficiency in potassium. I thought it was really strange because the food I ate all contained potassium. Then I got on the web and it said that if you show low on potassium, but eat potassium-laden foods, it may be a lack of magnesium. Lack of magnesium doesn't always show. I started taking magnesium and haven't had a racing heart since. Prior to that, I was taken to the Emergency room twice, thinking I was dying, and had several episodes at home.