Pituitary Adenoma Overview

The pituitary gland is a pea-sized gland located at the base of the brain between the optic nerves just behind the eyes.  It secretes hormones. Hormones are chemicals that travel through the blood stream. The pituitary gland is sometimes referred to as the "master hormone gland" as it controls hormone functions such as the body’s temperature, thyroid activity, growth during childhood, urine production, testosterone production in males and ovulation and estrogen production in females. It works as the body’s thermostat controlling all other glands responsible for hormone secretion.

Pituitary adenomas are noncancerous tumors that occur in the pituitary gland. The majority of tumors found in the pituitary gland are curable. However, the tumors can become big enough to damage nearby nerves and brain tissues.  By pressing on the nerves to the eyes (optic nerves), a pituitary tumor can cause gradual vision loss and blindness.  Sometimes, the tumor compresses the pituitary gland preventing it from producing the normal amount of hormones.  Hypothyroidism, adrenal insufficiency, and lack of growth hormone can occur.

There are different types of pituitary adenomas.  Many produce excess hormones which can cause major symptoms.  Increased production of growth hormone can cause a disease called acromegaly.  Too much prolactin hormone can cause impotence in men and the loss of menstrual periods, infertility, and breast milk production unrelated to childbirth (also called galactorrhea) in women.  Too much adrenocorticotropic hormone (ACTH) can cause Cushing’s disease.  Chromophobe adenomas are nonfunctional tumors (they do not secrete active hormones) but may cause hormone deficiency by compressing the normal pituitary. 

There is no known cause of pituitary adenomas.  Most occur spontaneously, meaning they are not inherited.  Some are inherited but these are not common.  Some research suggests that the use of birth control pills may be a factor in some patient cases.  Also, some patients with multiple endocrine neoplasia type 1 (MEN-1) have pituitary tumors.  MEN-1, previously known as Wermer syndrome, is a hereditary condition associated with tumors of the endocrine (hormone producing) glands.

The symptoms that pituitary adenomas produce depend upon several factors, including whether the tumors are hormone-producing or nonfunctioning and tumor size.  Large tumors can compress the optic chiasm causing vision loss.  Large pituitary tumors can also put too much pressure on the normal pituitary gland and cause pituitary failure. 

Pituitary adenomas can suddenly bleed internally. This can cause a quick increase in size. The tumor can also outgrow its blood supply. This can lead to swelling of the dead tissue. Patients who have any of these medical emergencies generally experience a sudden headache and vision loss.

Treatment depends of the type of tumor—whether it is functioning (hormone-producing) or non-functioning (does not secrete active hormones), tumor size, whether it has grown beyond the area of the pituitary gland, and the person’s age and general health.  Prolactin-secreting tumors (prolactinomas) may become stable and improve with time.  People with these tumors usually benefit from treatment with medication and may not require surgery.  Tumors that produce other hormones are treated with surgery or radiation.  A surgery commonly done is a transsphenoidal hypophysectomy (an operation that goes through the sinus cavities to remove the pituitary tumor).  It is usually the treatment chosen for tumors that have not grown outside the bony cavity.  Large tumors, usually nonfunctioning adenomas, need additional treatment with radiation.  Tumors that produce growth hormone and ACTH usually grow slowly.  With any of the pituitary tumors, however, surgery is called for immediately if there is rapid vision loss. 

Patients may also want to consider participation on a clinical trial as a treatment option.  A clinical trial is meant to obtain information on new treatments for patients with cancer.  It is important to discuss all options with your doctor and together decide which treatment is best for you.

Glossary of Terms

Hypothyroidism:  Condition in which the thyroid gland does not make enough thyroid hormone

Adrenal insufficiency: Condition in which the adrenal glands produce insufficient amount of one or more of the hormones:  glucocorticoids, mineralocorticoids, and androgens

Prolactin:  A hormone released by the pituitary gland that stimulates breast development and milk production in women

 Acromegaly:  a long-term condition in which there is too much growth hormone and the body tissues get larger over time.

Cushing’s disease:  Condition that occurs when the pituitary gland makes too much of the hormone ACTH