Hmmm testing my biology anatomy here... thyroid is regulated by the thyroid, pituitary gland and the hypothalmus...any one of them out of whack and you get a problem (like everything else?) I think it's associated with Graves disease (easily fixed..what causes ppl's eyes to bulge)... and weight loss...

If you have been taking something for weight loss that might show high... if you have been eating a lot of iodine contained foods (even enriched salt) that might be the reason.. (fish etc)

I know ppl with low activity of thyroid are always cold but don't know if overactive would make you hot

What sort of problems were you having that you had it checked?