What is the thyroid-stimulating hormone (TSH) test?
This blood test measures how well your thyroid gland is working. This gland, which is located at the lower front of the neck, may be underactive or overactive. The test measures your body’s response to the thyroid hormone level in your blood. Your body controls the activity of your thyroid gland by producing thyroid-stimulating hormone (TSH). A high TSH level means that your thyroid gland is underactive. When your thyroid gland is underactive and not producing enough thyroid hormone, your body produces more TSH to stimulate the gland and increase its activity. A low TSH level means that your thyroid gland is overactive. When your thyroid gland is overactive and producing too much thyroid hormone, your body decreases the amount of TSH to slow production of thyroid hormone.
