thyroid question

Your TSH value being low, alone, is fairly meaningless if your other thyroid levels are OK and you have no clinical symptoms of hyperthyroidism.  My TSH tends to run lowish (.3-.5)  but my T4, Free T3, etc. are fine.   My medcation is the same at 160lbs as it was at 291 largely because I have retained the same amount of muscle mass -- i.e., metabolically active tissue.  

I have Graves' Disease, and I am now hypothyroid but I was severely hyperthyroid when first diagnosed.   I underwent I-131 therapy 17 years ago which knocked out my thyroid.  When I was hyperthyroid, my heat rate, resting, was about 100.  Right now, it's 55-60. I'm not hyperthyroid although a lot of doctors would look just at TSH and adjust my meds.

Just as a note endocrinologists have revised DOWN the 'normal' range for TSH.  Anything over 3 is considered too high, now.