Low thyroid levels are fairly common especially in postmenopausal women.
Checking your thyroid levels is very important. Low thyroid levels for a long time can cause changes to skin, hair, and can make you feel tired and cold. You may even gain a little bit of weight or become constipated. It can even change your cholesterol levels.
If you doctor prescribes thyroid medications, your health care provider will check TSH levels. TSH is Thyroid Stimulating Hormone. It comes from your pituitary gland in the Limbic system.
The TSH stimulates your thyroid to produce more thyroid hormone. If your thyroid levels are too much, your TSH level will be low. If your thyroid hormones from your thyroid gland or from your medication is too much, then your TSH will be very low.
Too much thyroid can be dangerous, especially over a long time. As you get older, your TSH levels should be a little higher – in other words your thyroid hormones a little lower – than when you are younger. Too much thyroid is more harmful to your body than too little.
Here is a great link to the THYROID GLAND.
I hope that makes sense.