Pituitary Gland
In vertebrate anatomy, the pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and weighing 0.5 grams (0.018 oz) in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain. The hypophysis rests upon the hypophysial fossa of the sphenoid bone in the center of the middle cranial fossa and is surrounded by a small bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The anterior pituitary (or adenohypophysis) is a lobe of the gland that regulates several physiological processes (including stress, growth, reproduction, and lactation). The intermediate lobe synthesizes and secretes melanocyte-stimulating hormone. The posterior pituitary (or neurohypophysis) is a lobe of the gland that is functionally connected to the hypothalamus by the median eminence via a small tube called the pituitary stalk (also called the infundibular stalk or the infundibulum).
Hormones secreted from the pituitary gland help control: growth, blood pressure, certain functions of the sex organs, thyroid glands and metabolism as well as some aspects of pregnancy, childbirth, nursing, water/salt concentration and the kidneys, temperature regulation and pain relief.
Pituitary disease is a disorder primarily affecting the pituitary gland.
The main disorders involving the pituitary gland are:
| Condition | Direction | Hormone |
| Acromegaly | overproduction | growth hormone |
| Cushing’s disease | overproduction | adrenocorticotropic hormone |
| Growth hormone deficiency | underproduction | growth hormone |
| Syndrome of inappropriate antidiuretic hormone | overproduction | vasopressin |
| Diabetes insipidus (can also be nephrogenic) | underproduction | vasopressin |
| Sheehan syndrome | underproduction | any pituitary hormone |
| Pickardt-Fahlbusch-Syndrome | underproduction | any pituitary hormone, except prolactin, which is increased |
| Hyperpituitarism (most commonly pituitary adenoma) | overproduction | any pituitary hormone |
| Hypopituitarism | underproduction | any pituitary hormone |
Overproduction or underproduction of a pituitary hormone will affect the respective end-organ. For example, insufficient production (hyposecretion) of thyroid stimulating hormone (TSH) in the pituitary gland will cause hypothyroidism, while overproduction (hypersecretion) of TSH will cause hyperthyroidism. Thyroidisms caused by the pituitary gland are less common though, accounting for less than 10% of all hypothyroidism cases and much less than 1% of hyperthyroidism cases.