The pituitary is a pea-sized gland that is attached to an area at the base of the brain called the hypothalamus. The pituitary gland is part of the endocrine system; a system of glands that produce and regulate hormones, affecting processes throughout the body. The hypothalamus communicates with the rest of the brain and nervous system. It senses the body’s need for more or less of a particular hormone and controls the amount of hormone released from the pituitary.
Pituitary disorders are characterised by an excess or a deficiency in one or more of the hormones produced by the pituitary gland. When the disorder is caused by a pituitary tumour, symptoms such as headache and loss of vision may be present due to compression of the surrounding tissues.
The pituitary consists of a front (anterior) and back (posterior) portion. In the anterior pituitary, growth hormone (GH), adrenocorticotrophic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinising hormone (LH), follicle-stimulating hormone (FSH) and prolactin are produced. They affect particular “target” tissues throughout the body, including the thyroid gland, adrenal glands, ovaries (women), and testes (men). In the posterior pituitary, oxytocin and antidiuretic hormone (ADH), produced in the hypothalamus, are stored for release. Some of the normal functions of these hormones are described below.
- Prolactin: stimulates breast milk production after childbirth.
- LH and FSH: required for the development of sexual characteristics at puberty; fertility.
- GH: regulates bone growth and muscle mass
- ACTH: regulates the body’s response to stress via stimulation of the production of cortisol by the aderenal glands.
- TSH: stimulates the thyroid gland to produce thyroid hormones, which regulate the rate at which the body uses energy (the metabolic rate)
- ADH: controls the amount of water that the kidneys excrete, which in turn helps regulate the balance of water in the body.
- Oxytocin: stimulates the contraction of the uterus during and after childbirth and is responsible for stimulating the release of milk during breastfeeding.