Treatment of Functional (Hormone-Making) Pituitary Tumors

The treatment of functional pituitary adenomas (tumors that make excess hormones) depends on which type of hormone they make.

Treatment of lactotroph adenomas (prolactinomas)

Unlike most other pituitary tumors, surgery is usually not the first treatment for these prolactin-secreting tumors.

Sometimes these tumors can just be watched, without treating them right away. If the tumor isn’t very large and isn’t causing bothersome symptoms, blood prolactin levels can be checked regularly. If they start to go up, an MRI can be done to see if the tumor is growing.

If treatment is needed, medicines known as dopamine agonists (cabergoline or bromocriptine) are used first. (See Medicines to Treat Pituitary Tumors.) They usually lower prolactin levels and shrink (or slow the growth of) prolactinomas well enough so that surgery isn't needed.

These drugs usually lower prolactin levels within a few weeks, and they often shrink tumors within a few months (although sometimes this takes longer).

If treatment with one of these medicines works, a person might take it for the rest of their life. However, if treatment continues to work over time (typically at least 2 years) and MRI scans no longer show a tumor, stopping the medicine may be an option. You would still need regular checks of prolactin levels to see if the tumor comes back.

If the tumor doesn’t respond well enough to the initial dose of the drug, going to a higher dose or switching to a different drug might be tried. If this isn’t helpful, or if the side effects of the drug are too bothersome, surgery is usually done to try to remove the tumor. 

Radiation therapy may be used after surgery to try to lower the risk of the tumor coming back, especially for larger tumors (macroadenomas). It might also be an option if drug treatment and surgery do not work.

For women with prolactinomas who want to become pregnant, a dopamine antagonist can be used both to treat the tumor and help restore regular menstrual cycles. However, these drugs haven’t been studied extensively during pregnancy, so to be safe they are usually stopped once a woman becomes pregnant. If the tumor grows large enough during the pregnancy to cause symptoms, the drug can be started again.

Treatment of somatotroph adenomas (growth hormone-secreting tumors)

Pituitary tumors that make too much growth hormone (GH) can cause acromegaly in adults and gigantism in children. (For more on these conditions, see Signs and Symptoms of Pituitary Tumors.)

Surgery is usually the first treatment for these adenomas. The goal is to remove all of the tumor, although this isn’t always possible, especially for larger tumors. Sometimes, octreotide or lanreotide (somatostatin analogs) might be given for a few months before surgery. This may shrink the tumor and help with other symptoms, which might improve the chance of removing the tumor completely.

Blood levels of GH and insulin-like growth factor-1 (IGF-1) will be checked a few months after surgery, typically along with an MRI to look for signs of tumor. If any tumor remains, options might include a second surgery (if it can be done) or drug treatment with a somatostatin analog. Radiation therapy might be another option, but it's used most often when surgery and drug treatments don't work. (This is because radiation is often very slow to work, and over time it can lead to low levels of other pituitary hormones.)

For people who can’t have surgery for some reason (or who don’t want surgery), treatment with a somatostatin analog is typically the first treatment.

If the somatostatin analog isn’t working, other types of drugs might be tried, such as pegvisomant (a GH antagonist), or cabergoline or bromocriptine (dopamine agonists). For more on the drugs used to treat these tumors, including how they’re given and possible side effects, see Medicines to Treat Pituitary Tumors.

Treatment of corticotroph adenomas (ACTH-secreting tumors)

These tumors cause the adrenal glands to make excess steroid hormones such as cortisol, which can lead to Cushing's disease. (See Signs and Symptoms of Pituitary Tumors.)

Surgery is usually the main treatment for these tumors, if possible. If the surgery doesn’t remove the tumor completely or if it grows back, further treatment options include a second surgery or radiation therapy. Radiation can often take many months to work, so medicines to help control cortisol levels may be given in the meantime.

If surgery and radiation don't control cortisol levels, or if these treatments can't be used for some reason, other options may include using medicines or removing both of the adrenal glands (see below).

Several types of medicines might be helpful for ACTH-secreting tumors, such as pasireotide (a somatostatin analog) or cabergoline (a dopamine agonist). Other medicines can help keep the adrenal glands from making cortisol, or can help limit the effects of cortisol in the body. But some of these drugs can have serious side effects that make them hard to take for a long time. (For more on these drugs, see Medicines to Treat Pituitary Tumors.)

If these treatments aren't helpful, or if a person can't take medicines because of their side effects, both adrenal glands can be removed in an operation called a bilateral adrenalectomy. This can usually be done with laparoscopic surgery, making small incisions in the belly instead of one large one. The surgeon works through these small incisions with special long, thin instruments, including one with a tiny video camera on the end to look into the belly. This surgery stops all cortisol production, so high cortisol levels will no longer be a problem. But after surgery a person will need to take pills to replace the adrenal steroid hormones for the rest of their life.

If the adrenal glands are going to be removed, the pituitary gland will first be treated with radiation. If this isn't done, removing the adrenals can cause the pituitary tumor to get larger and even start growing into the structures near the pituitary. This is known as Nelson syndrome. If the adenoma gets large enough, it can damage the remaining normal parts of the pituitary gland, causing problems from hormone deficiency. It can also lead to high levels of ACTH. Because ACTH is a lot like the hormone that causes tanning, the high ACTH levels can darken the skin.

Treatment of thyrotroph adenomas (TSH-secreting tumors)

These rare tumors make too much thyroid-stimulating hormone (TSH), which causes the thyroid to make excess thyroid hormones.

The main treatment for these tumors is typically surgery. This usually works well for smaller tumors, although larger tumors are often harder to remove completely. It’s important to restore thyroid hormone levels to normal before surgery. This is usually done by giving a somatostatin analog such as octreotide (see Medicines to Treat Pituitary Tumors) for several months before the surgery. This might also help shrink the tumor and help make the surgery easier.

If surgery doesn’t remove the tumor completely, or if it can’t be done for some reason, treatment options might include drugs (a somatostatin analog such as octreotide or lanreotide, or a dopamine agonist such as cabergoline or bromocriptine) or radiation therapy. Each of these treatments can have pros and cons. For example, if medicines are effective, they’ll need to be taken for the rest of a person’s life. Radiation often takes many months to work, so medicines like those above often need to be given in the meantime. Radiation might also cause side effects such as damage to the normal parts of the pituitary, while medicines can have their own side effects.

Regardless of which type of treatment is used, it’s important to watch for signs of the tumor coming back after treatment. This can be done with blood tests of thyroid hormone levels as well as MRIs.

Treatment of gonadotroph adenomas (FSH/LH-secreting tumors)

The hormones made by these tumors – follicle-stimulating hormone (FSH) and luteinizing hormone (LH) – often don’t cause symptoms, so these tumors usually aren't found until they grow large enough to cause symptoms by pressing on nearby structures. That is, almost all of these tumors are essentially non-functional adenomas and are treated as such. For more information, see Treatment of Non-Functional Pituitary Tumors.