Used in diagnostic testing for thyroid function, particularly to assess the responsiveness of the pituitary gland in patients with suspected hypothalamic or pituitary disorders. It stimulates the release of thyroid-stimulating hormone (TSH) and prolactin from the anterior pituitary. This response helps differentiate between primary, secondary, and tertiary causes of thyroid dysfunction. Also used in research settings to study neuroendocrine pathways and hypothalamic-pituitary-thyroid axis regulation.