. TSH is used to evaluate the function of the thyroid gland, which regulates metabolism, energy production, and overall growth and development.
. TSH is produced by the pituitary gland and stimulates the thyroid to produce T3 and T4.
. TSH is typically the most sensitive test for assessing thyroid function, with high TSH indicating hypothyroidism and low TSH indicating hyperthyroidism. It is usually the first test performed, and abnormal results to be followed by FT3 and FT4 to clarify the diagnosis.
. It is also used to monitor treatment for thyroid disorders (especially in those taking thyroid hormone replacement or anti-thyroid medications), to evaluate conditions such as Graves' disease, Hashimoto's thyroiditis, or thyroid nodules, and to detect non-thyroidal illness (conditions affecting thyroid hormone levels independently of thyroid function).