A nurse is reviewing the laboratory results of a patient newly diagnosed with hypothyroidism. The patient's TSH level is significantly elevated. Which explanation best describes why TSH would be high in a patient with hypothyroidism?
- The thyroid gland releases TSH directly in response to low circulating thyroid hormone levels.
- High TSH levels are a normal compensatory response seen only in hyperthyroidism.
- Elevated TSH indicates the thyroid gland is overproducing hormones and requires suppression.
- The anterior pituitary releases more TSH to stimulate a thyroid gland that is producing insufficient T3 and T4.