Hypopituitarism is a condition where the amount of hormone being produced is not sufficient and replacement hormones are necessary to maintain normal body function.

Normal pituitary function may be lost as the result of a pituitary tumor, which can compress the gland resulting in impaired function or it can be destroyed entirely.  Other common causes of impaired pituitary fuction or the destruction of the gland are surgery and radiation therapy. Hypopituitarism can also be caused by damage to the hypothalamus (e.g., radiation damage). Regardless of the cause, hormone replacement is required.

No. Some patients have only a single hormone deficiency, others have 2 or 3 deficiencies, and in some patients, all pituitary hormones are deficient.

Pituitary tumors are common. In autopsy studies of patients who did not have known pituitary disease, as many as 26% had a small tumor (adenoma) in the gland. Molecular biology studies have shown that a change in the DNA of pituitary cells can cause unregulated growth of a particular cell type resulting in a pituitary tumor, called an adenoma. There are no known environmental causes. Very uncommonly, pituitary tumors may be inherited.

The pituitary gland is NOT in the brain and pituitary tissue is different from brain tissue. The link between the two tissues is only by a thin stalk.

In over 99% of patients this is not the case, the tumour is benign. Althought it is benign the physical presence of the tumour can also cause the normal pituitary gland to become underactive (hypopituitarism) by damaging the gland, therefore it's abilty to produce hormones or the tumour itself can produce hormones e.g lactinoma