Hypopituitarism

Definition:

An abnormal condition caused by a deficiency of one or more hormones secreted by the pituitary gland.

Causes, incidence, and risk factors:

The pituitary gland is a pea-sized structure that is located at the base of the brain, and is attached by a stalk to the hypothalamus, an area of the brain that controls the function of the pituitary gland.

The hormones secreted by the pituitary and their functions are:

• growth hormone, which stimulates cell division and bone growth
• thyroid stimulating hormone, which stimulates the thyroid gland to secrete hormones that affect body metabolism
• adrenocorticotropic hormone, which stimulates the adrenal gland to secrete hormones that affect metabolism
• prolactin, which stimulates female breast development and milk production
• luteinizing hormone, which controls sexual function in males and females
• follicle stimulating hormone, which controls sexual function in males and females
• melanocyte stimulating hormone, which controls pigmentation of the skin
• antidiuretic hormone, which controls water loss by the kidneys
• oxytocin, which stimulates contraction of the uterus during labor and milk release from the breasts.

In hypopituitarism, single or multiple hormone deficiencies are present. The deficiencies affect the target organ activity or secretion (the thyroid; the adrenals; or the gonads, which includes both female and male sexual development and function). Causes of hypopituitarism are tumors or lesions of various origins, congenital defects, trauma, radiation, surgery, encephalitis, hemochromatosis, and stroke. In children, the condition results in slowed growth and development and is known as dwarfism. The cause may also be unknown.

Risk factors are related to the cause and may include previous history of diabetes insipidus, previous history of adrenal insufficiency, previous history of a pituitary tumor, cessation of menses in a premenopausal woman, and short stature. The incidence is 1 out of 10,000 people.