I believe 70 mcg is the RDA for selenium. You can take too much of it. If you're getting it in your diet as well, you might be careful. I split 200 mcg tablets in half, take half the first day, half the second and none the third day.
Too much FT3 can definitely cause chest pain (angina).
I'm only taking 200mcg at bedtime of the Selenium.
Can too much FT3 cause the chest pains and the strange feelings right below my collar bone? I'll let you know what I find out about my labs.
I might try that extra split on my pills. That kind of math screws with my brain! Haha!;)
I seriously doubt you did any damage to your heart adding an extra quarter grain. You might have just gotten your FT3 a bit high for you.
Have you thought about a more even split between morning and afternoon? You're taking 1.5 in the a.m. and 0.25 in the p.m., correct? Perhaps you'd get a more even FT3 level throughout the day splitting it 1.25/0.5 or 1.0/0.75??? Either of those would give you more of a boost in the afternoon without raising your FT3 as much.
How much selenium are you taking?
Oh, I also had just started to take a Selenium supplement almost around the same time....