After taking a Standard Process supplement that had a thyroid supplement in it for over a year, my chiro upped my dosage and I started noticing some heart palpitations (this was in Nov 2013). One day, my heart starting racing unabated and I went to the hospital where I was diagnosed with a-fib. After an overnight stay and many blood samples and tests, I was told my heart was completely healthy. When I followed up with the doc I saw in the hospital (she had run some tests on my thyroid), she had found that my TSH was 14. I have had a couple of episodes since then where my heart doesn't race, but it doesn't feel right and I feel light-headed have had to lie down. When the episode is over, I feel fine. My doc has run some more tests on my thyroid and has repeated the TSH and had an ultrasound f my thyroid done - I'll get the results Thursday.