Hypothalamic–pituitary–gonadal axis Hypothalamic–pituitary–gonadal axis The hypothalamic–pituitary–gonadal axis (HPG axis) refers to the hypothalamus, pituitary gland, and gonadal glands as if these individual endocrine glands were a single entity. Because these glands often act in concert, physiologists and endocrinologists find it convenient and descriptive to speak of them as a single system. The HPG axis plays a critical part in the development and regulation of a number of the body's systems, such as the reproductive and immune systems. Fluctuations in this axis cause changes in the hormones produced by each gland and have various local and systemic effects on the body. The axis
Anterior pituitary adrenal insufficiency can be caused by hypo-secretion of ACTH which, in turn, does not signal the adrenal cortex to produce a sufficient amount of cortisol. This is a life-threatening condition. Hypopituitarism could be caused by the destruction or removal of the anterior pituitary tissue through traumatic brain injury, tumor, tuberculosis, or syphilis, among other causes. This disorder used to be referred to as Simmonds' disease but now according to the Diseases Database it is called Sheehan syndrome. If the hypopituitarism is caused by the blood loss associated with childbirth, the disorder is referred to as Sheehan syndrome. The anterior pituitary