I spent the night in the ER about 4 weeks ago after having chest pains and was told that my TSH level was at 63. They gave me IV synthroid and told to take my prescribed dosage. I followed up with my GP and was told to increase my dosage of synthroid to 150 mg until they got my blood work back. The next day my GP told me to take 150 mg 6 days a week and 300 mg on the 7th. After 3.5 weeks (while at the gym) I started to have chest discomfort. I went back to my GP and was told that my levels are within range and that the heart palps aren't related to the thyroid. She did change my dosage to 175 mg each night. I've been on synthroid for over 16 years and never had this issue. The only change was being treated for anemia with iron infusions and starting to have chest pains in November. My dosage was dropped in December to about 100 mg - 125 mg to see if that fixed the issue. Unfortunately, it ended up with me being in the hospital for chest pains. Not sure what is causing them now since I'm back to my normal dosage?