Pituitary Tumor

What the pituitary gland does

The pituitary sits in a bony pocket (the sella turcica) just below the optic chiasm, where the nerves from both eyes cross. It releases hormones that control:

• prolactin: breast milk production
• growth hormone: growth and metabolism
• ACTH: the adrenal glands and cortisol
• TSH: the thyroid
• LH and FSH: the ovaries and testes
• ADH (from the back of the gland): water balance

Types of pituitary tumors

Tumors under 1 cm are microadenomas; those 1 cm or larger are macroadenomas. Rarer growths in the area include craniopharyngiomas, Rathke's cleft cysts and meningiomas. True pituitary cancer is very rare.

Symptoms

From hormone excess

Depend on the hormone (see table). Prolactinomas are the most common functioning type.

From pressure on nearby structures

• vision loss: classically loss of the outer half of the visual field in both eyes (bitemporal hemianopia), noticed as bumping into things or car accidents
• headaches
• double vision or a drooping eyelid if nerves to the eye muscles are compressed

From hormone deficiency

A large tumor can squeeze normal pituitary tissue, causing hypopituitarism:

• fatigue, weakness, low blood pressure (low cortisol)
• feeling cold, weight gain (low thyroid)
• irregular or absent periods, low libido, erectile dysfunction, infertility (low sex hormones)
• poor growth in children

Pituitary apoplexy

Sudden bleeding or loss of blood supply in a tumor causes severe headache, vision loss, eye movement problems and collapse. It is an emergency.

Diagnosis

• blood tests: prolactin, IGF-1 (growth hormone), cortisol tests, thyroid tests, LH, FSH, testosterone or estradiol
• dynamic tests: glucose suppression test for acromegaly, dexamethasone suppression and late-night salivary cortisol for Cushing's
• MRI of the pituitary with contrast
• formal visual field testing by an eye specialist

Incidentally found small tumors are checked for hormone activity and usually monitored with periodic MRI.

Treatment

Medicines

• prolactinomas: dopamine agonists (cabergoline or bromocriptine) shrink the tumor and normalize prolactin in most people, often without surgery
• acromegaly: somatostatin analogs, pegvisomant
• Cushing's disease: cortisol-lowering drugs when surgery is not curative
• hormone replacement for deficiencies: hydrocortisone, thyroid hormone, sex hormones, growth hormone, desmopressin

Surgery

Transsphenoidal surgery through the nose (endoscopic or microscopic) removes most pituitary tumors without opening the skull. It is first-line for symptomatic non-functioning tumors, acromegaly, Cushing's disease and TSH-secreting tumors. Vision often improves quickly after decompression.

Radiation

Stereotactic radiosurgery or fractionated radiation for tumors that remain or regrow after surgery. It can cause gradual loss of pituitary function over years.

Monitoring

Small, non-functioning tumors without symptoms are often watched with MRI and hormone tests.

Outlook

Most pituitary tumors are controllable, and many people return to normal life. Some need lifelong hormone replacement and regular follow-up with an endocrinologist, MRI scans and eye tests.

Frequently asked questions

What are the symptoms of a pituitary tumor?

Symptoms include headaches, loss of side vision, and hormone-related changes such as milky nipple discharge, missed periods, low libido, enlarged hands and feet, weight gain with high blood pressure, or fatigue from hormone deficiency. Many small tumors cause no symptoms.

Is a pituitary tumor cancer?

Almost never. Nearly all pituitary tumors are benign adenomas that do not spread. They can still cause problems through hormone excess or pressure on the optic nerves and normal pituitary tissue. Pituitary carcinoma is very rare.

How is a pituitary tumor treated?

Prolactinomas are usually treated with medicine. Most other symptomatic tumors are removed by surgery through the nose. Radiation is used for remaining or recurrent tumor. Small, silent tumors may only need monitoring. Hormone replacement treats deficiencies.

Can a pituitary tumor affect your eyesight?

Yes. A large tumor can press on the optic chiasm, where the nerves from both eyes cross, causing loss of the outer side vision in both eyes. Vision often improves after the pressure is relieved.

What is pituitary apoplexy?

Pituitary apoplexy is sudden bleeding into or loss of blood supply to a pituitary tumor. It causes a sudden severe headache, vision loss, eye movement problems and sometimes collapse from low cortisol. It needs emergency treatment.