Hypothalamic-pituitary-thyroid axis

The hypothalamic-pituitary-thyroid axis (HPT axis for short) is part of the endocrine system responsible for the regulation of metabolism.

As its name suggests, it depends upon the hypothalamus, the pituitary gland, and the thyroid gland.

The hypothalamus senses low circulating levels of thyroid hormone (T3 and T4) and responds by releasing thyrotropin releasing hormone (TRH). The TRH stimulates the pituitary to produce thyroid stimulating hormone (TSH). The TSH, in turn, stimulates the thyroid to produce thyroid hormone until levels in the blood return to normal. Thyroid hormone exerts negative feed back control over the hypothalamus as well as anterior pituitary thus controlling the release of both TRH from hypothalamus and TSH from anterior pituitary gland