TRH, also known as thyrotropin-releasing factor, is secreted by the anterior region of the hypothalamus, along with a number of identified and well-characterized releasing hormones. TRH infusion has been used in clinical testing to determine if the pituitary gland is responsive to its stimulation in producing thyroid-stimulating hormone (TSH). While the lack of production of TRH may result in a deficiency of TSH, TRH is not routinely measured in clinical laboratories to assess thyroid function.