Hypothalamic–pituitary–thyroid axis Hypothalamic–pituitary–thyroid axis The hypothalamic–pituitary–thyroid axis (HPT axis for short, a.k.a. thyroid homeostasis or thyrotropic feedback control) is part of the neuroendocrine 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 (Triiodothyronine (T3) and Thyroxine (T4)) and responds by releasing thyrotropin-releasing hormone (TRH). The TRH stimulates the anterior 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 feedback
Combined rapid anterior pituitary evaluation panel by TRH and rises in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) caused by GnRH. Blood glucose levels are also monitored to ensure appropriate levels of hypoglycemia are achieved. The triple bolus test was introduced in 1973 by physicians from the London Royal Postgraduate Medical School and Queen Elizabeth Hospital, Birmingham. It followed earlier reports combining insulin and vasopressin analogues in the diagnosis of hypopituitarism. Combined rapid anterior pituitary evaluation panel A triple bolus test or a dynamic pituitary function test is a medical diagnostic procedure used to assess a patient's pituitary function. A triple bolus test is usually ordered