Thyroid Function Tests Blood tests for thyroid disease can be
broken down into tests of thyroid function (i.e. how much
thyroid hormone is being made), thyroid mass (i.e. how much
thyroid tissue there is), and antibodies to thyroid tissue.
Tests of thyroid function: - TSH (thyroid stimulating hormone or
thyrotropin): The pituitary gland makes TSH to stimulate the
thyroid to make and release more thyroid hormone. When there is
enough or too much thyroid hormone in the body, the TSH level
drops. When there is too little thyroid hormone in the body, the
TSH level rises. Therefore, if a patient is hyperthyroid (i.e.
has too much thyroid hormone), theirTSH level should be low or
"suppressed" because the brain does not want to stimulate the
thyroid to make any more thyroid hormone. If a patient is
hypothyroid (i.e. has too little thyroid hormone), there TSH
level should be high because the brain is trying to get the
thyroid to make more thyroid hormone. - Free T4 (thyroxine): T4
is the most common form of thyroid h