Pituitary dictionary

ACTH

• Adrenocorticotrophic hormone (ACTH) is a hormone released from the pituitary gland in response to CRH from hypothalamus. ACTH acts on the adrenal glands which in turn produces hormones such as cortisol.

FSH

• Follicle stimulating hormone is released by the pituitary and acts on the gonads. In men it stimulates the production of spermatozoa and in woman it plays a role in the development of ovarian follicles.

Gamma-knife

• Gamma-knife radiosurgery is a technique for delivering focused radiotherapy. Gamma-knife radiosurgery to the pituitary is usually indicated when surgery is not possible or preferred.

Growth hormone

• GH is released from the pituitary gland in response to GHRH from the hypothalamus. Growth hormone excess in children results in gigantism and in adults, acromegaly.

Hormone replacement

• The replacement of hormones that are deficient. This is commonly association with HRT and women, but the term is not infrequently used to indicate replacement of other hormones in for example hypopituitarism.

Hyperprolactinaemia

• Raised blood prolactin level. This may be caused by a variety of conditions including a benign pituitary tumour, certain medication and fibroids. 

Hypopituitarism

• A state in which the pituitary gland is producing inadequate amounts of hormones. The causes for this may be pituitary surgery, radiation or a pituitary tumour.

Hypophysectomy

• The surgical removal of the pituitary gland. The indication for this is usually a large pituitary tumour.

Hypothalamus

• This is a part of the brain that lies above the pituitary and communicates with the pituitary through hormones such as Corticotrophin releasing hormone (CRH), gonadotrophin releasing hormone (GnRH) and growth hormone releasing hormone (GHRH) to regulate release of hormones from the pituitary gland.

LH

• Luteinising hormone is released by the pituitary and acts on the gonads. In males, it results in testosterone production by the testis. In women it plays a role in ovarian follicle development and ovulation. 

Optic chiasm

• The optic chiasm is a structure that lies above the pituitary gland and is formed of the two nerves as they cross towards each eye. The optic chiasm can be compressed and therefore vision effected in large pituitary tumours.

Pituitary

• A gland that is situated just below the brain that releases various hormones including ACTH, LH, FSH, prolactin and vassopressin. 

Pituitary macroadenoma

• A pituitary tumour that is larger than 1cm in diameter. Pituitary tumours are virtually all benign.

Pituitary microadenoma

• A pituitary tumour that is smaller than 1cm in diameter. Pituitary tumours are virtually all benign.

Vassopressin

• Vassopressin is a hormone released from the posterior (back) portion of the pituitary gland. It acts on the kidneys to help retain water in the body. A deficiency of this hormone results in diabetes insipidus.