The pituitary is a tiny pea-sized gland at the base of the brain. It serves as the body's "command center," producing hormones that regulate growth and metabolism as well as the actions of other glands, including the thyroid, adrenals and gonads (ovaries in women and testes in men).
Tumors arising from the cells of the pituitary gland are also known as pituitary adenomas. They are almost always benign, but can have significant side effects when they produce excessive amounts of hormones, grow large enough to affect normal pituitary function or interfere with surrounding structures, particularly the optic nerves, which are responsible for sight.
Types of Pituitary Tumors
Pituitary tumors can be divided into two broad categories:
Non-functioning tumors don't produce hormones. Symptoms are generally associated with the tumor's growth and its effects on nearby structures, including the optic nerve and other cranial nerves. Non-functioning tumors may also interfere with the pituitary gland's normal production of hormones.
Functioning tumors are those that produce excessive amounts of specific hormones, each with its own set of symptoms.
Types of Functioning Tumors
Thyroid-stimulating hormone (TSH): Tumors that overproduce this hormone cause the thyroid to release excessive amounts of thyroxine, which can lead to hyperthyroidism (overactive thyroid), although pituitary tumors are a rare cause of this condition. Symptoms include:
- Weight loss
- Rapid or irregular heartbeat
Prolactin: Prolactin stimulates breast growth and milk production in women. A pituitary tumor that overproduces this hormone is called a prolactinoma. Symptoms in women include a milky discharge from the nipples, irregular menstrual periods or the absence of menstruation. Symptoms in men include:
- Erectile dysfunction and/or impotence
- Loss of body hair
- Decreased sex drive
- Rarely, increased breast growth (gynecomastia)
Growth hormone (GH): GH regulates linear growth in children and has various effects on the body's metabolism. Tumors that overproduce GH result in acromegaly in adults and gigantism in children.
Symptoms of acromegaly include:
- Gradual enlargement of the hands, feet, jaw and/or forehead
- Coarse facial features, such as thickened skin and enlarged nose or lips
- Heart problems
- High blood pressure
- Excessive sweating
Adrenocorticotropic hormone (ACTH): This hormone stimulates the adrenal glands to produce cortisol, which plays a role in the body's response to stress and helps regulate blood pressure and heart function, among other duties. Overproduction of ACTH leads to Cushing's disease.
Symptoms of Cushing's disease include:
- Rounded "moon" face
- Weight gain, particularly in the trunk and abdomen
- Thinning of the skin
- Purple-red stretch marks
- High blood pressure
Pituitary carcinoma: In rare cases, a pituitary tumor can become cancerous and metastasize (spread) to other areas of the body. In most cases, pituitary carcinomas do produce hormones, particularly prolactin and ACTH. Symptoms would be similar to tumors producing those hormones, but may also include symptoms from the tumor's growth affecting nearby areas such as the optic nerve.
Specific symptoms depend on the type of hormone secreted by a pituitary tumor. Symptoms resulting from the size of the tumor may include headaches, double vision and loss of vision due to impingement of the optic nerves.