A nurse is talking with a client whose thyroid-stimulating hormone (TSH) level will be measured. Which of the following statements by the nurse explains the purpose of this test?

A. "This test determines whether your thyroid gland is overactive, appropriately active, or underactive.": The TSH test is used to assess the function of the thyroid gland by measuring how much thyroid-stimulating hormone is being produced by the pituitary gland. High or low TSH levels indicate whether the thyroid is overactive or underactive. B. "This test detects antithyroid antibodies in your blood.": This describes a test for autoimmune thyroid diseases, such as Hashimoto's thyroiditis or Graves' disease, not a TSH test. C. "This test measures the absorption of iodine and how it relates to the thyroid gland.": This describes an iodine uptake test, which is used to assess thyroid function, but it is not the purpose of a TSH test. D. "This test measures the amount of thyroid hormone that attaches to a protein in your blood.": This describes a test for thyroid-binding globulin (TBG) levels, not the TSH test. TSH measures the amount of thyroid-stimulating hormone in the blood, not thyroid hormone attachment.