Is a TSH test the best way to detect an underactive thyroid?
TSH (Thyroid Stimulating Hormone) is a substance that is produced by a part of the brain called the pituitary gland. TSH stimulates the thyroid to produce more hormone when the brain senses that thyroid hormone levels are low. When thyroid hormone levels are high, the pituitary stops making TSH. Some people refer to the TSH as the “thermostat” of thyroid hormone production. If thyroid hormone levels are a little low, the TSH is a little elevated; if thyroid levels are very low, the TSH is very elevated. The blood test for TSH is the most accurate way to tell if thyroid hormone levels are in a normal range. TSH levels are typically checked at least once a year after a stable dose of thyroid medication has been established. When doses are changing, TSH is measured more often to determine when the right dose has been reached. TSH is considered to be in a normal range when it is between 0.5 and 4.9 mU/mL. Recently, experts (American Association of Clinical Endocrinologists) have discussed
