Ginagirl is absolutely correct. Hypothyroidism is all about your body temp. The T4, T3, TSH and etc is just a bunch of BS designed to keep you confused and dependent on your doctor. Your thyroid's MAIN job is to control your metabolism (body Temp). If there is anything at all wrong in the complex loop between your brain & the liver & Thyroid, your body temp suffers first.
The fact is that these T4,T3,TSH numbers are more dependent on the Halogen Toxins that have displaced the Iodine in your thyroid & the glands in your body. Your thyroid does not like the toxic chemicals of Bromide, Fluoride, & Chlorine that are invading our body every day from food & water. Your thyroid wants Iodine and none other or else it goes into decline causing hypothyroid & even goiter & cancer. Ditto your breasts, ovaries & uterus require Iodine or they revolt with fibrocystic breasts, PCOS, cysts Endo and related cancers. http://www.freegrab.net/Iodine%20update.htm#section18
These toxic halogen chemicals take over and result in severe iodine deficiency.
It is possible that after taking iodine & detoxing your body, that your thyroid may not recover. It could be damaged by iodine deficiency for so many years. In this rare case, you will need to take Natural Thyroid Meds to get your body temp back to normal. http://www.stopthethyroidmadness.com/site-map/
But even then, your thyroid can recover with continued iodine and you will discover that you can reduce your thyroid meds.