The pituitary gland is connected directly to part of the brain called the hypothalamus. This provides a key link between the brain and the endocrine system, a collection of glands in the body that make hormones. Hormones are substances released into the blood that control how other organs work. The hypothalamus releases hormones into tiny blood vessels connected to the pituitary gland. These then cause the pituitary gland to make its own hormones. The pituitary is considered the “master control gland” because it makes the hormones that control the levels of hormones made by most of the other endocrine glands in the body.

The pituitary gland has 2 parts, the anterior pituitary and the posterior pituitary. Each has distinct functions.

Anterior pituitary

Most pituitary tumors start in the larger, front part of the pituitary gland known as the anterior pituitary. This part of the gland makes these hormones that control other endocrine glands:

• Growth hormone (GH, also known as somatotropin) promotes body growth during childhood. If too much is made in a child they will grow very tall. Normally, adults make only small amounts of growth hormone. If an adult makes too much growth hormone, the bones of the hands, feet, and face continue to grow and become quite large, causing their normal features to become distorted. (This condition is called acromegaly.)
• Thyroid-stimulating hormone (TSH, also called thyrotropin) stimulates growth of the thyroid gland and the release of thyroid hormone. Thyroid hormone regulates metabolism. Too much makes you hyperactive and shaky, and too little makes you sluggish. If a pituitary tumor makes too much TSH, it can cause hyperthyroidism (an overactive thyroid gland).
• Adrenocorticotropic hormone (ACTH, also known as corticotropin) causes the adrenal glands to grow and to make steroid hormones (such as cortisol). Too much ACTH from the pituitary causes Cushing’s disease, the symptoms of which can include rapid weight gain and the build-up of fat in certain parts of the body.
• Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are also called gonadotropins. In women their main effects are on the ovaries, where they control ovulation (the release of eggs) and the production of the hormones estrogen and progesterone. In men, LH and FSH control testosterone and sperm production in the testicles.
• Prolactin causes milk production in the female breast. Its function in men is not known.

Posterior pituitary

The smaller, back part of the pituitary gland, called the posterior pituitary, is really an extension of brain tissue from the hypothalamus. The posterior pituitary is where hormones made by the hypothalamus (vasopressin and oxytocin) are stored and released into the bloodstream.

• Vasopressin (also called antidiuretic hormone, or ADH) causes the kidneys to keep water in the body and not lose it all in the urine. Without vasopressin, a person urinates too much and becomes dehydrated. This condition is called diabetes insipidus. Vasopressin also can raise blood pressure by causing blood vessels to constrict. It might have other functions as well.
• Oxytocin causes the uterus to contract in women during childbirth and the breasts to release milk when a woman nurses her baby. It might have other functions in both men and women.

Tumors rarely start in the posterior pituitary.

Pituitary tumors

Almost all pituitary tumors are benign (not cancer) glandular tumors called pituitary adenomas. These tumors are called benign because they don’t spread to other parts of the body, like cancers can. Still, even benign pituitary tumors can cause major health problems because they are close to the brain, may invade nearby tissues (like the skull or the sinuses), and because many of them make excess hormones.

Pituitary cancers (called pituitary carcinomas) are very rare.

Pituitary adenomas

These benign tumors do not spread outside the skull. They usually stay in the sella turcica (the tiny space in the skull that the pituitary gland sits in). Sometimes they grow into the boney walls of the sella turcica and nearby tissues, like blood vessels, nerves, and sinuses. They don’t grow very large, but they can have a big impact on a person’s health.

There is very little room for tumors to grow in this part of the skull. So, if the tumor gets larger than about a centimeter (about half an inch) across, it may grow upward, where it can press on and damage nearby parts of the brain and the nerves that arise from it. This can lead to problems like vision changes or headaches. (See Signs and Symptoms of Pituitary Tumors.)

Microadenoma versus macroadenoma

Pituitary adenomas can be divided into 2 categories based on size:

• Microadenomas are tumors that are smaller than 1 centimeter (cm) across. Because these tumors are small, they rarely damage the rest of the pituitary or nearby tissues. But they can cause symptoms if they make too much of a certain hormone. Many people actually have small adenomas that are never found because they don't grow large enough or make enough hormones to cause a problem.
• Macroadenomas are tumors 1 cm across or larger. Macroadenomas can affect a person’s health in 2 ways. First, they can cause symptoms if they make too much of a certain hormone. Second, they can cause symptoms by pressing on normal parts of the pituitary or on nearby nerves, such as the optic nerves.

Functional versus non-functional adenoma

Pituitary adenomas are also classified by whether they make too much of a hormone and, if they do, which type they make. If a pituitary adenoma makes too much of a hormone it's called functional. If it doesn’t make enough hormones to cause problems it's called non-functional.

Functional adenomas: Most of the pituitary adenomas that are found make excess hormones. The hormones can be detected by blood tests or by tests of the tumor when it is removed with surgery. Based on these results, pituitary adenomas are classified as:

• Lactotroph adenomas make prolactin and account for about 4 out of 10 pituitary tumors.
• Somatotroph adenomas make growth hormones and make up about 2 in 10 pituitary tumors.
• Corticotroph adenomas make ACTH and account for about 1 in 10 pituitary tumors.
• Gonadotroph adenomas make LH and FSH and are very rare.
• Thyrotroph adenomas make TSH and are very rare.
• Plurihormonal adenomas make more than one hormone.
• Null cell adenomas do not make hormones. (These are non-functional adenomas.)

The kind of hormone an adenoma makes strongly affects what signs and symptoms it causes. It also affects which tests are used for diagnosis, the choice of treatment, and the patient’s outlook.

Non-functional adenomas: Pituitary adenomas that don’t make excess hormones are called non-functional adenomas or null cell adenomas. They account for about 3 in 10 of all pituitary tumors that are found. They are usually found as macroadenomas, causing symptoms because of their size as they press on nearby structures.

Pituitary carcinomas

Cancers of the pituitary gland are rare. Only a few hundred have ever been described in medical journals. They can occur at any age, but most are found in older people. These cancers usually make hormones, just like many adenomas do.

Pituitary carcinomas look like pituitary adenomas under a microscope, so doctors have trouble telling them apart. In fact, the only way to tell if a pituitary tumor is a carcinoma and not an adenoma is when the tumor spreads to another part of the body not near the pituitary gland. Most often pituitary carcinoma spreads to the brain, spinal cord, meninges (the covering of the brain and spinal cord), or bone around the pituitary. Rarely, these cancers spread to other organs such as the liver, heart, or lungs.

One of the key issues with pituitary tumors is that there's currently no way to know if a benign pituitary adenoma will become cancer and grow and spread to other parts of the body.

Other tumors of the pituitary region

There are several other types of benign tumors that grow in the region of the pituitary, as well as some malignant (cancerous) ones. All are much less common than pituitary adenomas.

Teratomas, germinomas, and choriocarcinomas are all rare tumors that usually occur in children or young adults. They don’t develop from the hormone-making cells of the pituitary gland itself, but they can grow into the pituitary and damage it.

Rathke cleft cysts and gangliocytomas of the pituitary are rare tumors that are usually found in adults.

Craniopharyngiomas are slow-growing tumors that start above the pituitary gland but below the brain itself. They sometimes press on the pituitary and the hypothalamus, causing hormone problems. They'e more common in children, but they can be seen in older adults. For more on these tumors, see Brain and Spinal Cord Tumors in Children.

Cancers that start in some other parts of the body (like the breast) can sometimes spread to the pituitary. These cancers are classified and treated based on where they started (their primary site) and are not thought of as pituitary tumors.

The rest of our information focuses mainly on benign pituitary tumors (pituitary adenomas).

Pituitary tumors are usually found when a person goes to the doctor because of symptoms they're having. But sometimes these tumors don’t cause symptoms, and they're found when doing medical tests done for other health problems.

If there’s a reason to suspect you might have a pituitary tumor, your doctor will use one or more tests to find out. Signs and symptoms might suggest that you could have a pituitary tumor, but tests are needed to be sure of the diagnosis and find out what kind of pituitary tumor it is.

Medical history and physical exam

If your symptoms lead your doctor to believe that you might have a pituitary tumor, the first step is take a complete medical history to check for risk factors and to learn more about your symptoms. Your doctor may ask about your family history of tumors or other problems to see if you might have an inherited genetic syndrome, such as multiple endocrine neoplasia, type I (MEN1).

Your doctor will also examine you to look for possible signs of a pituitary tumor or other health problems. This may include exams to look for vision or nervous system problems that could be caused by a tumor.

If a pituitary tumor is strongly suspected, your doctor may refer you to an eye doctor to check your vision, as pituitary tumors can damage nerves leading to the eyes. The most common test is to measure how well you can see. The doctor may also test your field of vision (or visual fields). At first, pituitary tumors only press on part of the optic nerves. This often leads to the loss of peripheral vision, meaning that you can't see things off to the side without actually looking right at them. Eye doctors have special instruments that can test for this.

You might also be referred to other doctors, such as an endocrinologist (a doctor who treats diseases in glands that secrete hormones) or a neurosurgeon (a doctor who uses surgery to treat brain and pituitary tumors), who might order other tests.

Blood and urine tests of hormone levels

If your doctor suspects you might have a hormone-producing pituitary tumor, hormone levels in your blood and/or urine will be measured.

Somatotroph (growth hormone-secreting) adenoma

A physical exam may alert the doctor to look for this tumor because the signs and symptoms are often very distinctive.

The next step is to check the levels of growth hormone and insulin-like growth factor-1 (IGF-1) in your blood samples, which are taken in the morning after an overnight fast. When growth hormone levels are high, they cause the liver to make more IGF-1. Testing the IGF-1 level can be more helpful than checking the level of growth hormone. IGF-1 level doesn’t change much during the day, while the level of growth hormone can go up and down.

If both levels are very high, the diagnosis is clearly a pituitary tumor. If the levels are slightly increased, another test called a glucose suppression test is often done to be sure. You'll be asked to drink a sugary liquid, then the levels of growth hormone and blood sugar will be measured at certain times. The normal response to suddenly taking in so much sugar is a drop in growth hormone levels. If the growth hormone levels stay high, a pituitary adenoma is likely the cause.

Corticotroph (corticotropin or ACTH-secreting) adenoma

Most of the signs and symptoms of ACTH-secreting tumors come from having too much cortisol (an adrenal steroid hormone). But quite a few diseases can cause the body makes too much cortisol, which is called Cushing’s syndrome. If you have symptoms suggesting this syndrome, you'll need tests to see if it’s caused by a pituitary tumor or something else.

One of the tests used measures the levels of cortisol in your saliva late at night to see if they stay elevated. (They normally drop at night.) Another may include measuring levels of cortisol and ACTH in blood samples taken at different times of the day. You also may be asked to collect all of your urine over a 24-hour period, which is then tested to measure your daily production of cortisol and other steroid hormones. One test involves taking a dose of a powerful, cortisone-like drug called dexamethasone, then checking blood or urine cortisol levels. Often more than 1 of these tests is needed to help distinguish ACTH-secreting pituitary tumors from other diseases, such as adrenal gland tumors, that can cause similar symptoms.

Lactotroph (prolactin-secreting) adenoma (also called a prolactinoma)

Blood prolactin levels can be measured to check for a prolactinoma.

Gonadotroph (gonadotropin-secreting) adenoma

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) blood levels can be checked to see if you have a gonadotropin-secreting tumor. Levels of related hormones, such as estrogen, progesterone, and testosterone, are often checked as well.

Thyrotroph (thyrotropin-secreting) adenoma

Tests to measure blood levels of thyrotropin (TSH) and thyroid hormones can usually identify people with a thyrotropin-secreting adenoma.

Null cell (non-functional) adenoma

A pituitary adenoma is considered non-functional if it doesn’t make too much of any pituitary hormone. Pituitary hormone levels are not high in people with non-functional tumors. Sometimes, though, blood levels of pituitary hormones may actually be low because the adenoma crowds out the cells that normally make these hormones.

Testing for diabetes insipidus

Diabetes insipidus can occur if the part of the pituitary that stores the hormone vasopressin (ADH) is damaged, which leads to too much water being lost in the urine. This condition can be caused by pituitary macroadenomas (or carcinomas in rare cases), or by tumors starting in parts of the brain or nerves next to the pituitary gland. It can also be a side effect of surgery to treat pituitary tumors or tumors near the pituitary gland.

In many cases, this diagnosis is made with tests that measure the amount of urine made over a 24-hour period, sodium and glucose levels in the blood, and osmolality (total salt concentration) of the blood and urine. If these test results are not clear, then a water deprivation study may be done. In this test, you are not allowed to drink fluids for several hours. The test is often done overnight. If your body is not making enough vasopressin, you'll continue to make urine even though you are not taking in any fluid. You may also be given an injection of vasopressin to see if this corrects the problem.

Venous blood sampling

Corticotroph (ACTH-secreting) adenomas may be too small to be seen on imaging tests such as MRI scans. When the ACTH level is high, but a person’s MRI is normal, a special blood test may be useful to find the tumor.

For this test , catheters (long, soft, small tubes) are put into veins on each inner thigh through tiny cuts in the skin and are guided all the way up into the petrosal sinuses near the base of the brain. The sinuses hold 2 small veins that drain the blood from each side of the pituitary gland. Blood is taken from these 2 veins and your arm. Then an injection of corticotropin-releasing hormone (CRH, a hormone from the hypothalamus that normally causes the pituitary to make ACTH) is given. Blood samples are taken again to see if the ACTH level goes up a lot, or is higher on one side than the other. If it is, the source of the high ACTH level is a pituitary tumor.

Imaging tests

Imaging tests use x-rays, magnetic fields, or other means to create pictures of the inside of your body. They may be done to look for pituitary tumors or to see if they have grown into nearby structures. In some cases, an imaging test of the head done for another reason may show a pituitary tumor.

Magnetic resonance imaging (MRI) scan

MRI scans use radio waves and strong magnets to create detailed pictures of the inside of the body.

They are very helpful in looking at the brain and spinal cord and are considered to be the best way to find pituitary tumors of all types. MRI images are usually more detailed than those from CT scans (see below). They can show macroadenomas of the pituitary gland, as well as most microadenomas. But MRI might not detect microadenomas that are smaller than 3 mm (about 1/8 inch) across. Sometimes the MRI scan will show a small change in the pituitary that has nothing to do with the patient’s symptoms. Between 5% and 25% of healthy people have some minor abnormality of the pituitary gland that shows up on an MRI scan.

Computed tomography (CT) scan

A CT scan uses x-rays to create detailed cross-sectional images of part of your body. CT scans can find a pituitary adenoma if it's large enough, but MRI scans are used much more often to look at the brain and pituitary gland.

Tests of pituitary tissue samples

In diagnosing tumors of most parts of the body, imaging tests and blood tests may strongly suggest a certain type of tumor, but a biopsy (removing a sample of the tumor to examine under a microscope) is usually the only way to be certain of the diagnosis. In many cases, doctors won't treat a tumor until a biopsy has been done.

But a biopsy isn't usually needed before treating a pituitary tumor. One reason is that the hormone tests for some types of adenomas are very accurate, so a biopsy isn’t likely to provide much more information. Biopsies in this part of the body can also pose a very small risk of serious side effects. On top of this, some types of adenomas can be treated without surgery, using medicines or radiation therapy.

When pituitary tumors are removed by surgery, they're examined under a microscope to determine their exact type. Special stains may be used on the tumor to color the areas making hormones and other tests may be done, too. This helps classify the tumor.

For most people with pituitary tumors, treatment can remove or control the tumor. The end of treatment can be both stressful and exciting. You may be relieved to finish treatment, but it’s hard not to worry about the tumor growing or coming back. This is a very common concern in people who have had a pituitary tumor.

It may take a while before your fears lessen. But it may help to know that many pituitary tumor survivors have learned to live with this uncertainty and are living full lives.

For other people, the tumor might never go away completely. Some people may continue to get medicines or other treatments to help keep the tumor in check. Learning to live with a tumor that doesn't go away can be difficult and very stressful. It has its own type of uncertainty.

Follow-up care

Follow-up care is very important after treatment for pituitary tumors. Even if you have completed treatment, your doctors will still want to watch you closely. Keep all of your appointments with your health care team and follow their instructions carefully. Report any new or returned symptoms to your doctor right away. Ask questions if you don’t understand what your doctor says.

Surgery is often the first treatment for many types of pituitary adenomas. If you had a functional (hormone-making) pituitary adenoma, hormone level tests can often be done within days or weeks after surgery to see if treatment workedl. Blood tests will also be done to see how well the remaining normal pituitary gland is working. If the results show that the tumor was removed completely and that pituitary function is normal, you'll still need regular visits with your doctor. Your hormone levels may need to be checked again in the future to check to see if the adenoma comes back. Whether or not the tumor made hormones, MRI scans are often done as a part of follow-up. Depending on the size of the tumor and the extent of surgery, you may also be seen by a neurologist to check your brain and nerve function and an ophthalmologist (eye doctor) to assess your vision.

After radiation treatment, you will need check-ups for several years. The response of the tumor to radiation therapy is hard to predict, and while the benefits and side effects of treatment can be seen within months, some might take years to know how well it worked. Your pituitary function will be checked at regular intervals. MRI scans will be the main follow-up tests, along with testing hormone levels if your tumor made hormones.

It’s common for people to have low pituitary hormone levels after surgery or radiation therapy. These people will need hormone replacement. Thyroid hormone and adrenal steroids can be taken as pills. In men, testosterone can be given to restore sex drive and help prevent osteoporosis (weak bones). Testosterone is available as a gel, liquid, or patch applied to the skin. It can also be given as a monthly injection or implanted as a pellet under the skin every few months. In young women, estrogen is given either by pills or a skin patch to avoid early menopause. Often, progesterone is given along with estrogen. Pituitary hormone deficiency can affect a woman’s ability to have children. But it may be possible with hormone therapy.

If you're taking medicine for a prolactinoma, you will have your hormone levels checked at least once or twice a year. If an MRI shows that the tumor has shrunk after treatment, the MRI might not need to be repeated, depending on the size of the tumor and whether the response is partial or complete. If you have a prolactin-producing microadenoma, you may be able to stop drug treatment after several years of therapy. Your doctor might recommend stopping the drug and then checking your prolactin level. If it stays normal, you may be able to stay off the drug.

For patients getting drug therapy for corticotropin (ACTH)-producing or growth hormone-producing adenomas, follow-up may be more frequent. Your hormone levels and symptoms will be watched carefully. People with growth hormone-producing adenomas have an increased risk of developing high blood pressure and heart failure. They also have a higher risk of getting colon cancer. Periodic check-ups for these conditions are recommended.

Diabetes insipidus (see Signs and Symptoms of Pituitary Tumors) can be a short-term result of surgery, but in some cases it might last longer. It can usually be treated. If the problem is mild, simply taking in enough fluids might treat this problem. For more severe problems, the drug called desmopressin is given either by nasal spray or by tablet. It's always important to drink enough fluids to avoid dehydration.

It’s also important to consider whether your pituitary tumor might be a clue to a genetic syndrome in your family. Some people with pituitary tumors might be able to have genetic tests done to look for certain gene changes. If a change is found, family members might want to be tested as well to see if they are at increased risk.

Sometimes people with large or fast-growing pituitary adenomas may be disabled or have their lives shortened because the tumor or its treatment destroys vital brain tissue near the pituitary gland, but this is rare. In general, when a pituitary tumor is not cured, people live out their lives but may have to deal with problems caused by the tumor or its treatment, such as vision problems or hormone levels that are too high or too low.

Ask your doctor for a survivorship care plan

Talk with your doctor about developing a survivorship care plan for you. This plan might include: 

• A suggested schedule for follow-up exams and tests
• A schedule for other tests you might need in the future, such as early detection (screening) tests for cancer, or tests to look for long-term health effects from your tumor or its treatment
• A list of possible late- or long-term side effects from your treatment, including what to watch for and when you should contact your doctor
• Diet and physical activity suggestions
• Reminders to keep your appointments with your primary care provider (PCP), who will monitor your general health care 

Keeping health insurance and copies of your medical records

Even after treatment, it’s very important to keep health insurance. Tests and doctor visits cost a lot, and even though no one wants to think of their tumor coming back, this could happen.

At some point after your treatment, you might find yourself seeing a new doctor who doesn’t know about your medical history. It’s important to keep copies of your medical records to give your new doctor the details of your diagnosis and treatment. Learn more in Keeping Copies of Important Medical Records.

Can I lower my risk of the pituitary adenoma progressing or coming back?

If you have (or have had) a pituitary tumor, you probably want to know if there are things you can do that might lower your risk of it growing or coming back, such as exercising, eating a certain type of diet, or taking nutritional supplements. Unfortunately, it’s not yet clear if there are things you can do that will help.

Adopting healthy behaviors such as not smoking, eating well, getting regular physical activity, and staying at a healthy weight might help, but no one knows for sure. But we do know that these types of changes can have positive effects on your health.

About dietary supplements

So far, no dietary supplements (including vitamins, minerals, and herbal products) have been shown to help lower the risk of a pituitary tumor growing or coming back. This doesn’t mean that no supplements will help, but it’s important to know that none have been proven to do so.

Dietary supplements are not regulated like medicines in the United States – they don't have to be proven effective (or even safe) before being sold, but there are limits on what they’re allowed to claim they can do. If you’re thinking about taking any type of nutritional supplement, talk to your health care team. They can help you decide which ones you can use safely while avoiding those that might be harmful.