Pituitary Tumors: About Pituitary Tumors

Approximately 7 percent of brain tumors develop in the pituitary gland. Tumors in the pituitary gland are diagnosed in some 1,300 people in the United States each year.

However, estimates from the American Cancer Society indicate that nearly one out of five people (15 to 20 percent) will develop a benign pituitary tumor within his or her lifetime. Often pituitary tumors go undetected until discovered through a routine imaging study, such as a MRI, for an unrelated health problem.

The Roles of the Pituitary Gland and Hypothalamus

The pituitary gland is a small gland at the base of the brain, located just above the back of the nose and near the optic nerves. The pituitary gland is connected to a part of the brain called the hypothalamus. This connection provides an important link between brain activity and the endocrine system — a system that produces and releases hormones, which travel through the bloodstream and control the actions of other cells or organs. The hypothalamus releases hormones that directly affect the pituitary gland and prompt the pituitary gland to make its own hormones. The pituitary gland — often called the “master control gland” — regulates the activity and function of most other glands in the body.

Here is a list of the primary hormones produced by the pituitary gland, including a brief description of what each does in the body:

• Adrenocorticotropic hormone (ACTH)

  This is the hormone that prompts, or stimulates, the adrenal glands to release cortisol. This is a hormone made by the adrenal cortex — the outer layer of the adrenal gland — that helps the body use glucose, protein, and fats. When the body makes too much ACTH, it causes a disorder known as Cushing's disease.

• Growth hormone (GH)

  This is the hormone that stimulates the growth of the body during childhood and adolescence. If too much GH is produced, this can cause a disorder known as acromegaly (in adults) or gigantism (in children).

• Prolactin (PRL)

  This is the hormone that stimulates a woman's breasts in preparation for lactation after pregnancy.

• Thyroid-stimulating hormone (TSH)

  This hormone stimulates the thyroid to release thyroid hormone. An abnormal level of TSH can cause the thyroid gland to become over- or underactive (hyperthyroidism or hypothyroidism).

• Follicle-stimulating hormone (FSH)

  This hormone stimulates the growth of ovarian follicles during the early phase of the menstrual cycle and assists in the production of sperm in males.

• Luteinizing hormone (LH)

  This is the hormone that prompts ovulation (the release of an egg from an ovary during the menstrual cycle) in females and stimulates the testicles to release testosterone in males.

Types of Pituitary Tumors

Almost all pituitary tumors are adenomas, or noncancerous tumors that do not require treatment unless they grow large enough to cause symptoms. Microadenomas are small tumors that are less than one centimeter (about 1/2 inch) in size, while macroadenomas are those tumors that are larger than one centimeter. Both microadenomas and macroadenomas can cause symptoms due to excess hormone secretion, but only macroadenomas are big enough to damage the pituitary gland and surrounding tissue.

Symptoms of a pituitary tumor may include headaches, vision problems, menstrual irregularities, lactation (when a woman is not pregnant), nausea, or vomiting. Pituitary tumors that are called functioning tumors produce hormones and can cause different symptoms depending on the type of hormone that is being made by the tumor. For example, if the tumor produces excessive luteinizing hormone, a woman might experience menstrual irregularities. The overproduction of growth hormone in children may cause a condition called gigantism. Its effects can include growing very tall, rapid growth, joint pain, and increased sweating.

The other types of pituitary tumors are called nonfunctioning tumors. They do not necessarily require treatment because they do not produce excessive hormones nor do they grow large enough to cause symptoms or damage to the surrounding structures in the brain.

Along with imaging, dynamic pituitary testing and visual field testing are used in the diagnosis of pituitary tumors to evaluate pituitary function before and after surgery.

Treatment

Treatment is usually necessary for both large nonfunctioning tumors and for functioning tumors. Depending on the type of tumor, therapy may include medication alone, or surgery with or without radiation therapy, plus medication. Some patients may take medicine every day to suppress excess hormone production and to prevent tumor growth.

Because treatment varies depending on the type of hormone that is secreted, visit the following link to learn more about specific types of pituitary tumors and associated treatments.