Pituitary Tumors: Patient Guide

The pituitary is a pea-sized gland at the base of the brain. It sits in a bony pocket called the sella turcica and directs much of the body's hormone system.

NCI's PDQ summary reports that pituitary tumors make up 10% to 25% of tumors inside the skull. The overwhelming majority are adenomas, which are benign. Pituitary carcinoma, the malignant form, accounts for only 0.1% to 0.2% of cases.

PDQ also notes that adenomas are present in roughly 17% of people, and many never cause symptoms at all. So the finding on a scan and the problem in the patient are two separate questions.

Trouble comes from two directions. Either the tumor makes a hormone it should not, or it grows large enough to press on something.

The dividing line is 10 mm across.

• A microadenoma is smaller than 10 mm. Most adenomas fall here.
• A macroadenoma is 10 mm or larger.

PDQ also describes a formal classification. A five-grade scheme runs from 0 through IV. It rates where the tumor sits in the sella and how far it invades. A second scale grades upward extension above the sella, from 0 to more than 30 mm, using letters A through D.

Upward extension is what threatens vision. The optic nerves cross directly above the gland.

PDQ gives the share each type holds in surgical specimens.

Prolactin-producing tumors are the most common, at 25% to 41%. Excess prolactin causes missed periods, reduced fertility, and milk production unrelated to nursing.

Growth hormone-producing tumors account for about 13%. In adults this causes acromegaly. NIDDK describes the changes. The nose, ears, hands, and feet enlarge. Skin thickens and turns coarse and oily. The voice deepens and sweating increases. The jaw and brow begin to protrude. PDQ adds carpal tunnel syndrome, sleep apnea, and joint problems. In children, before growth plates close, the result is gigantism.

ACTH-producing tumors account for about 10%. Excess ACTH drives the adrenal glands to overproduce cortisol, which is called Cushing disease. PDQ lists weakness in the muscles closest to the trunk. Fat shifts around the body. Stretch marks and thinning bones follow. NIDDK adds weight gain, a puffy face, and easy bruising. Wide purple stretch marks show up on the abdomen, breasts, hips, and under the arms.

Thyrotropin-producing tumors are rare, under 2%. They cause an overactive thyroid without the drop in TSH you would normally expect. PDQ notes they often make more than one hormone.

Nonfunctioning adenomas make up 30% to 35%. They secrete nothing useful. Their damage is mechanical.

PDQ names inappropriate pituitary hormone secretion and visual field deficits as the most characteristic presenting features. Headache is listed among the symptoms of several individual tumor types.

The classic visual pattern comes from pressure on the optic chiasm above the gland. People lose the outer edges of vision on both sides and often do not notice until they clip a doorframe or miss a car in the next lane.

Formal visual field testing detects this long before a patient reports it. Ask whether it has been done and whether it will be repeated.

PDQ describes apoplexy as sudden bleeding into the tumor or loss of its blood supply.

Go to an emergency department immediately, not to a clinic appointment, for the following combination:

• sudden severe headache, often described as the worst ever.
• vomiting.
• sudden loss of vision or a change in visual fields.
• double vision or a drooping eyelid, from paralysis of eye movement.

This can occur in a person who did not know they had a pituitary tumor. Tell the emergency team to consider a pituitary cause. An urgent MRI and stress-dose steroids may be needed.

Anyone taking steroid replacement because the gland is underactive has a second emergency to know about. MedlinePlus describes adrenal crisis as severe weakness with vomiting, belly or flank pain, dizziness from very low blood pressure, fever, or confusion. Call 911 or go to an emergency department for that combination, and call your team the same day if illness, vomiting or a missed dose means you cannot keep your steroid tablets down.

Imaging and blood work run in parallel.

PDQ names MRI as the imaging test of choice. It shows soft tissue detail and can be viewed in more than one plane. It specifies sagittal T1-weighted and coronal images with thin 3 mm slices. A standard brain MRI without dedicated pituitary sequences can miss a microadenoma.

Hormone testing depends on which syndrome is suspected.

For acromegaly, NIDDK explains why a single growth hormone level is useless: GH swings throughout the day. The reliable measure is IGF-I. Confirmation uses an oral glucose tolerance test. You drink a sugary liquid. Blood is then drawn every 30 minutes for 2 hours. Growth hormone should fall. If it stays high, that supports acromegaly.

For Cushing syndrome, NIDDK names three screening tests. One is a 24-hour urinary free cortisol collection. One is a late-night salivary cortisol sample. The third is a low-dose dexamethasone suppression test, in which cortisol should fall after the dose and does not.

One cause has to be excluded first. NIDDK gives the most common cause of Cushing syndrome overall. It is long-term, high-dose treatment with cortisol-like medicines. Bring a complete list, including inhaled and injected steroids.

Among people whose excess cortisol comes from their own body, NIDDK reports that pituitary adenomas account for about 8 out of 10 cases.

PDQ also links pituitary adenomas to inherited syndromes. Three are named: multiple endocrine neoplasia type 1, Carney complex, and familial acromegaly.

Prolactinomas are treated with pills, not an operation.

PDQ makes dopamine agonists first-line therapy for prolactin-producing tumors. The two named are bromocriptine and cabergoline. PDQ puts cabergoline's success rate above 90% in people with newly diagnosed prolactinomas. These drugs often shrink the tumor as well as normalize the hormone.

That is unusual in oncology, and it is the reason prolactin should be measured before anyone schedules surgery for a pituitary mass.

PDQ describes transsphenoidal microsurgery as standard for ACTH-, growth hormone-, and TSH-producing tumors. The surgeon reaches the gland through the nose and the sphenoid sinus, without opening the skull. Remission rates for ACTH-producing tumors run 70% to 90%. NIDDK puts the cure rate for pituitary Cushing disease as high as 90%. That figure assumes a highly experienced surgeon. It is a strong reason to ask how many of these cases your surgeon does.

PDQ notes that this approach is avoided when the tumor has a significant hourglass narrowing above the sella.

Medical therapy exists for other types too. PDQ lists somatostatin analogues for TSH-producing tumors. It lists ketoconazole for ACTH-secreting tumors. For acromegaly, NIDDK adds somatostatin analogs, dopamine agonists, and growth hormone-receptor antagonists.

Radiation is generally adjuvant, meaning it follows another treatment. Two numbers matter before agreeing to it. PDQ reports about a 30% risk of hypopituitarism at 10 years. That word means the gland becomes underactive. It also notes the full effect takes 2 to 10 years to appear.

That delay is the practical catch. Radiation does not fix a hormone excess quickly, so medical therapy usually bridges the gap.

• Was a dedicated pituitary MRI done, or a general brain MRI?
• Which hormones were measured, and were any low as well as high?
• Have I had formal visual field testing, and when is the next one?
• Is this tumor functioning or nonfunctioning, and how was that established?
• If surgery is proposed, how many transsphenoidal cases does this surgeon do per year?
• Will I need hormone replacement afterward, and who will manage it long term?

• https://www.cancer.gov/types/pituitary/hp/pituitary-treatment-pdq
• https://www.niddk.nih.gov/health-information/endocrine-diseases/acromegaly
• https://www.niddk.nih.gov/health-information/endocrine-diseases/cushings-syndrome
• https://medlineplus.gov/ency/article/000357.htm