Your pituitary gland, located at the base of the brain, is only about the size of a pea, but it does critical work.
“It’s the master hormone gland,” says UNC Health neurosurgeon John Engler, MD. “The pituitary gland controls production of growth hormones, sex hormones and steroid hormones. It produces lactation hormones for breastfeeding and controls the water balance in the body.”
A pituitary tumor can impair how the gland works, causing problems in your body. Each year, more than 10,000 people in the United States are diagnosed with a pituitary adenoma.
“It’s not clear what causes these tumors,” Dr. Engler says. “It’s nothing you did or were exposed to, and they’re typically not genetic or inherited.”
While doctors may not know why these pituitary tumors form, they can treat them.
Types of Pituitary Tumors
There are two categories of pituitary tumors: functioning, meaning they cause the pituitary gland to overproduce a hormone, or nonfunctioning, which means they’re not causing excess hormone production.
“A nonfunctioning tumor might be found incidentally, when you get a brain scan for another reason,” Dr. Engler says. “When they’re small, they typically don’t cause any problems. If they grow, they can put pressure on other structures and cause headaches, changes to peripheral vision and hormone deficiencies.”
When the nonfunctioning tumor puts pressure on the pituitary gland, it won’t release all of the needed hormones, which can cause symptoms like fatigue, irregular menstrual cycles and low libido.
Nonfunctioning tumors grow slowly, and people may have one and not know; according to studies of autopsies, as much as 15 percent of population may have a pituitary tumor that doesn’t cause symptoms, Dr. Engler says.
Functioning pituitary tumors, which can also cause headaches and vision changes, are further classified by the type of hormone they affect:
- Prolactinomas, which account for about 40 percent of pituitary tumors, result in high levels of prolactin, the hormone necessary for breastfeeding. These tumors can affect both men and women and cause milky discharge from the breasts without pregnancy, irregular menstrual periods and loss of libido.
- Growth hormone-producing adenomas can cause gigantism in children, so that they grow very tall (the wrestler Andre the Giant had this kind of tumor), or, in adults, enlargement of certain parts of the body, like the hands, feet or nose. They account for 20 percent of pituitary tumors.
- Adrenocorticotropic hormone (ACTH) tumors stimulate excess production of cortisol in the adrenal glands, which can lead to Cushing’s disease. That causes unexplained weight gain, particularly around the belly and the neck, muscle weakness, high blood pressure and mood changes. About 10 percent of pituitary tumors are ACTH tumors.
- More rarely, pituitary tumors can cause overproduction of thyroid-stimulating hormone, which affects your metabolism, heart rate and body temperature, and follicle-stimulating hormone or luteinizing hormone, both of which are involved in sexual development and reproduction.
It is extremely rare for any of these tumors to be cancerous—less than 0.1 percent of pituitary tumors are—but treatment for functioning tumors is important.
“When pituitary tumors are significantly producing hormones, there are long-term considerations,” Dr. Engler says. “Overproduction of breast milk might lead to osteoporosis and bone fractures, excess growth hormone affects the heart and excess cortisol causes diabetes.”
Diagnosis and Treatment of Pituitary Tumors
If your doctor found a nonfunctioning pituitary tumor on a scan when looking for something else, you may not need any treatment.
“If it’s small, we can watch it,” Dr. Engler says. “You might start seeing an ophthalmologist so we know if there are any changes to vision. If it grows and starts to affect the optic nerve or invade an adjacent structure, we would operate.”
When your doctor suspects your symptoms are due to abnormal hormones, they will order blood work to check your levels; if something is abnormally high, they will order an MRI to look at the pituitary gland.
“With a prolactinoma, the treatment is medication, which usually shrinks the tumor and reestablishes normal hormone levels,” Dr. Engler says. “For all others, the first-line treatment is surgery.”
The pituitary gland’s location means that you won’t require traditional brain surgery—but you will need two surgeons.
“We access the pituitary gland through the nose, so that means we bring in an ear, nose and throat (ENT) specialist for the surgery,” Dr. Engler says, noting that the ENT specialist will provide access to the gland and the neurosurgeon will remove the tumor. “After surgery, there will be some nasal care with the ENT.”
Following surgery, you may work with an endocrinologist to make sure hormone levels have stabilized; you may need medication if there’s an imbalance. Sometimes radiation is necessary, Dr. Engler says, but for the most part, surgery resolves these issues for good.
“Regular follow-up is important, but most of these tumors have a low rate of recurrence,” Dr. Engler says. “The overall prognosis is very good.”
Questions about your hormones? Talk to your doctor or find one near you.