What is a pituitary adenoma?
A pituitary adenoma is a benign (noncancerous) growth on your pituitary gland. Unlike cancer, it doesn’t spread to other parts of your body. But as pituitary adenomas grow, they can put pressure on nearby structures and cause symptoms.
What is the pituitary gland?
Your pituitary is a small gland about the size of a pea that’s joined to your hypothalamus (the base of your brain) right behind your nose. It has two lobes: the anterior (front) lobe and the posterior (back) lobe. Each lobe releases different hormones.
Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, muscles and other tissues.
Your pituitary gland releases several important hormones, including:
- Adrenocorticotropic hormone (ACTH or corticotropin).
- Antidiuretic hormone (ADH, or vasopressin).
- Follicle-stimulating hormone (FSH).
- Growth hormone (GH).
- Luteinizing hormone (LH).
- Thyroid-stimulating hormone (TSH).
Your pituitary gland also tells other endocrine system glands to release hormones. Of note, pituitary adenomas can affect the production and release of a single hormone or a combination of hormones.
Healthcare providers categorize pituitary adenomas based on whether or not they produce extra hormones.
- Functioning (secreting) adenomas: These adenomas release extra pituitary hormones, which cause certain symptoms and/or conditions depending on the hormone it releases.
- Nonfunctioning (non-secreting) adenomas: These adenomas don’t release hormones, but they can compress nearby structures if they grow (see below). The most common adenomas most healthcare providers diagnose are nonfunctioning pituitary adenomas.
Healthcare providers also categorize pituitary adenomas based on their size:
- Microadenomas: These adenomas are smaller than 10 millimeters or 1 centimeter.
- Macroadenomas: These adenomas are larger than 10 millimeters. Macroadenomas are twice as common compared to microadenomas. They’re also more likely to cause lower than normal levels of one or more pituitary hormones. This is known as hypopituitarism.
Is a pituitary adenoma a brain tumor?
Even though your pituitary gland is an endocrine structure that’s not technically a part of your brain (it’s actually attached to your brain), healthcare providers consider pituitary adenomas brain tumors. They represent about 10% of primary brain tumors.
Who do pituitary adenomas affect?
Pituitary adenomas can occur at any age but are more common in people in their 30s or 40s. Women and people assigned female at birth (AFAB) are more likely to have pituitary adenomas than men and people assigned male at birth (AMAB).
How common are pituitary adenomas?
Pituitary adenomas make up 10% to 15% of all tumors that develop within your skull. About 77 out of 100,000 people have a pituitary adenoma, but researchers think adenomas actually occur in as many as 20% of people at some point in their lives. As many people with pituitary adenomas, especially microadenomas, are asymptomatic, they’re usually never found.
Symptoms and Causes
What are the symptoms of a pituitary adenoma?
The symptoms of pituitary adenomas can vary widely depending on several factors, including:
- If it’s large enough to damage your pituitary gland or nearby structures (mass effect).
- If it’s a functioning (hormone secreting) pituitary adenoma with symptoms based on the type of hormone it secretes.
Pituitary macroadenomas typically present with mass effects — meaning their large size can apply pressure to or damage nearby tissues, causing compressive symptoms, including:
Approximated 40% to 60% of people with a pituitary macroadenoma have impaired vision (blurry or double vision) from the adenoma. The adenoma compresses your optic chiasm, leading to visual field defects like the loss of peripheral vision (side vision).
People with pituitary adenomas often report having headaches. This could be due to pressure on nearby tissues, but as headaches are a common symptom in general, people could have them for other reasons as well.
Pituitary macroadenomas can cause one or more pituitary hormone deficiencies due to damage to your pituitary gland tissue. This can result in an underactive pituitary gland, also known as hypopituitarism.
Each pituitary hormone deficiency causes different symptoms.
- A deficiency of LH and FSH hormones leads to low testosterone (LH) and estrogen (FSH), a condition known as hypogonadism. Symptoms of hypogonadism include hot flashes and vaginal dryness in women and people AFAB, erectile dysfunction and decreased facial/body hair growth in men and people AMAB, mood swings, decreased libido/sex drive and fatigue.
- A deficiency of TSH results in low thyroid hormone production, a condition known as hypothyroidism. Symptoms of hypothyroidism include fatigue, constipation, slow heart rate, dry skin, swelling of extremities and diminished reflexes.
- A deficiency of ACTH means you don’t produce as much cortisol, a condition known as adrenal insufficiency. Symptoms of adrenal insufficiency include low blood pressure, nausea, vomiting, abdominal pain and poor appetite.
- A deficiency of GH results in low growth hormone production, also known as growth hormone deficiency. You’ll have different symptoms depending on how old you are. In adults, a lack of GH results in fatigue and decreased muscle mass.
What symptoms do functioning pituitary adenomas cause?
A functioning, or secreting, pituitary adenoma releases excess hormone(s). Functioning pituitary adenomas can cause several different symptoms depending on which pituitary hormone(s) they release.
As your body normally regulates the hormone levels in your body for optimum health, extra pituitary hormones from a functioning adenoma can lead to the following conditions:
Prolactinomas (lactotroph adenomas)
Prolactinomas (lactotroph adenomas) make excess prolactin, a condition known as hyperprolactinemia. Prolactinomas account for about 4 out of 10 pituitary tumors. They’re the most common type of pituitary adenoma.
High prolactin levels can disrupt normal reproductive functions by interfering with hormones produced by your testicles or ovaries. Symptoms include:
- Male and female infertility.
- Milky discharge from your nipples when not pregnant, which is known as (galactorrhea).
Somatotroph adenomas make excess growth hormone (also known as somatotropin) and make up about 2 in 10 pituitary tumors.
Somatotroph adenomas cause different symptoms depending on your age.
In adults, these adenomas are a common cause of acromegaly, a rare but serious condition that results from too much growth hormone. It affects your body’s bones and tissues and causes them to grow in abnormal ways. Over time, it can lead to enlarged hands, feet or head size and a rounded face with poorly defined features. It also affects important metabolic functions like blood sugar (glucose) regulation and can increase the size of your heart muscle.
In children and adolescents, somatotroph adenomas are the cause of gigantism (also called pediatric acromegaly and pituitary gigantism). High levels of growth hormone in their body cause them to grow very tall.
Corticotroph adenomas make extra adrenocorticotropic hormone (ACTH). They account for about 1 in 10 pituitary tumors. ACTH triggers your adrenal glands to make steroid hormones, including cortisol.
Corticotroph adenomas cause Cushing’s syndrome (excess cortisol). This causes several symptoms, including:
- High blood pressure.
- Muscle weakness.
- Easy bruising.
- Wide (> 1 centimeter), purple stretch marks over your belly.
- Compression fractures.
- Type 2 diabetes mellitus.
Thyrotroph adenomas make excess thyroid-stimulating hormone (TSH) and are very rare. TSH stimulates your thyroid gland to make and release thyroid hormone.
Hyperthyroidism has many other causes — pituitary adenomas are a rare cause of the condition.
Gonadotroph adenomas make excess gonadotropins, which are luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Gonadotroph adenomas are very rare.
These adenomas can cause irregular menstruation (periods) and ovarian hyperstimulation syndrome (OHSS) in women and people AFAB. In men and people AMAB, it can cause enlarged testicles, a deeper voice, balding on your temples and rapid facial hair growth.
They can also cause precocious (early) puberty in children.
What causes pituitary adenomas?
Scientists aren’t sure of the exact cause of pituitary adenomas.
But some adenomas have been linked to accidental changes, or mutations in DNA, the material within a cell that makes up our genes. These changes cause the cells in your pituitary gland to grow out of control, making a mass (growth). The genetic changes can be passed down from parents to children (inherited), but they usually happen randomly.
Pituitary adenomas are also associated with certain genetic conditions, including:
- Multiple endocrine neoplasia type 1.
- Multiple endocrine neoplasia type 4.
- Carney complex.
- X-LAG syndrome.
- Succinate dehydrogenase-related familial pituitary adenoma.
- Neurofibromatosis type 1.
- Von Hippel–Lindau syndrome.
Having one of these conditions makes it more likely that you’ll develop a pituitary adenoma, but you can still have an adenoma without having one of these conditions.
Diagnosis and Tests
How are pituitary adenomas diagnosed?
The diagnostic process for pituitary adenomas depends on what kind of adenoma you have and if it’s causing symptoms or not.
If you have a hormone-secreting pituitary adenoma, your healthcare provider will likely diagnose you with the condition it causes based on your symptoms before diagnosing the adenoma. This is because many conditions that result from excess hormones can have many different causes — not just pituitary adenomas. This is also true of hypopituitarism (pituitary hormone deficiency) causes.
Sometimes, healthcare providers find pituitary adenomas by accident when you get an imaging test of your brain for another condition. In these cases, the adenoma is usually small and nonfunctioning.
What tests will be done to diagnose a pituitary adenoma?
If your healthcare provider thinks you might have a pituitary adenoma, they’ll do a full review of your symptoms and your medical background and will perform a physical exam.
They may order any of the following tests:
- Blood tests: Depending on your symptoms, your healthcare provider may order blood tests to check certain hormone levels.
- Imaging tests: An MRI (magnetic resonance imaging) scan or CT (computed tomography) scan of your head can provide images of the structures inside of your head. These tests can confirm the diagnosis of a pituitary adenoma.
- Eye exam: If you’re having problems with your vision, your healthcare provider might have you take a visual field test to check your eye function. Large pituitary adenomas can put pressure on the nerves that connect your eyes to your brain and cause vision issues.
Management and Treatment
How is a pituitary adenoma treated?
Healthcare providers usually treat pituitary adenomas with surgery, medicine, radiation or a combination of these therapies. As each pituitary adenoma is different, you and your healthcare team will come up with a treatment plan that works best for you.
Surgery to remove pituitary adenomas
If you have a pituitary adenoma that’s causing a hormonal imbalance, your healthcare provider will likely recommend surgery to remove all or part of the adenoma. Depending on the size of the adenoma and the severity of your symptoms, you may need multiple surgeries.
Your surgeon will likely use a type of surgery called transsphenoidal surgery to remove the pituitary adenoma, which involves going through your nose and sphenoid sinus, a hollow space in your skull behind your nasal passages and below your brain, to perform surgery. Surgeons use this technique for 95% of pituitary tumors.
If the adenoma is too large to remove through your sinus cavity, your surgeon may open your skull (transcranial surgery) to get to your pituitary and the adenoma. This is a rare surgery technique for pituitary adenomas.
Medication to treat pituitary adenomas
Healthcare providers can treat some types of pituitary adenomas with medication that shrinks the adenoma and relieves symptoms.
If you have a prolactinoma (the most common kind of pituitary adenoma), you’ll likely receive dopamine agonist therapy medications, such as cabergoline (Dostinex®) or bromocriptine (Cycloset®), as the first course of treatment for several months.
In 80% of cases, these medications shrink the prolactinoma, and prolactin levels return to normal. If the medication doesn’t work, your healthcare provider will likely recommend surgery.
Radiation therapy for pituitary adenomas
Radiation therapy uses high-energy X-rays to shrink adenomas or tumors. Healthcare providers use a special form of radiation therapy called stereotactic radiosurgery for pituitary adenomas, which uses a high dose of radiation aimed precisely at the adenoma from more than one direction to keep the adenoma from growing.
What are the side effects of pituitary adenoma treatment?
As a result of surgeries and/or radiation therapy, approximately 60% of people with pituitary adenomas develop hypopituitarism after treatment, a condition in which there’s a lack of production of one, multiple, or all of your pituitary hormones. Hypopituitarism is treatable with hormone replacement medications.
Complications from surgery to remove a pituitary adenoma can include:
- Cerebrospinal fluid (CSF) leaks.
- Diabetes insipidus, which is a condition that results in partial or complete antidiuretic hormone deficiency from the posterior pituitary gland. This condition causes you to urinate large quantities of diluted urine resulting in sodium (salt) excess in your body.
Possible side effects of radiation therapy include:
- Pituitary hormonal deficiency.
- Impaired fertility.
- Vision loss and brain injury (rare).
- Tumor development several years after treatment (rare).
Can pituitary adenomas be prevented?
Unfortunately, there’s nothing you can do to prevent developing a pituitary adenoma. Most pituitary adenomas occur randomly, but they’re also associated with certain rare genetic conditions as noted above.
If you have a first-degree relative (sibling or parent) who has one of these conditions, you may want to get genetic testing to check to see if you have it as well. This may help screen for and catch a pituitary adenoma in its early phases. Your healthcare provider may recommend regular blood tests of your pituitary hormone levels to increase the odds of finding and treating a pituitary tumor before it creates problems.
Outlook / Prognosis
What is the prognosis (outlook) for pituitary adenomas?
The prognosis (outlook) depends on the size and type of pituitary adenoma you have.
When treatment destroys the adenoma, most people with adenomas can return to full, healthy lives. In some cases, adenoma treatment results in low hormone levels, and you have to take lifelong hormone medicines to replace what you’ve lost.
Adenomas tend to recur (come back), which means you may need treatment again. About 18% of people with nonfunctioning adenomas and 25% of people with prolactinomas will need more treatment at some point.
Can you live with a pituitary adenoma?
As long as a pituitary adenoma is small and doesn’t cause any symptoms, you can live with it. In fact, most people find out they have a pituitary adenoma when they get an imaging test of their head for another reason. But if the adenoma continues to grow, you may need to eventually receive treatment for it.
If you have a large and/or functioning pituitary adenoma, you’ll likely need treatment as some pituitary adenomas can cause symptoms that greatly impact your health and quality of life.
What are the complications of an untreated pituitary adenoma?
If left untreated, some pituitary adenomas — mainly macroadenomas and functioning (secreting) adenomas — can cause serious health issues. The health issues largely depend on which hormone the adenoma secretes (see Causes and Symptoms section above).
A very rare complication of untreated pituitary adenomas is pituitary apoplexy. This is a medical emergency that’s caused by bleeding either into or out of your pituitary gland.
Pituitary apoplexy is commonly caused by bleeding inside a pituitary adenoma. Your pituitary is damaged when the tumor suddenly enlarges. It either causes bleeding into your pituitary gland or blocks the blood supply to your pituitary. The larger the adenoma, the higher the risk for pituitary apoplexy.
Pituitary apoplexy usually has a quick onset of symptoms, which can be life-threatening. Symptoms often include:
- Severe headache.
- Paralysis of the eye muscles, causing double vision or problems opening an eyelid.
- Loss of peripheral vision or loss of all vision in one or both eyes.
- Low blood pressure, nausea and vomiting due to acute adrenal insufficiency.
- Personality changes due to the sudden narrowing of one of the arteries in your brain (anterior cerebral artery).
Although pituitary apoplexy is rare, it’s serious. If you have symptoms of pituitary apoplexy, call 911 or have a loved one take you to the nearest emergency room as soon as possible.
When should I see my healthcare provider about a pituitary adenoma?
Call your healthcare provider if you have problems with your vision and/or have headaches that don’t go away or keep coming back, particularly if they’re toward your forehead.
If you’ve been diagnosed with a pituitary adenoma, you’ll likely need to see your healthcare provider regularly to monitor the adenoma and to make sure your treatment is working.
A note from Cleveland Clinic
Finding out you have a tumor can be scary. The good news is that pituitary adenomas are almost always benign (noncancerous), and treatment leads to good outcomes in most cases. Remember that your healthcare provider is your partner in achieving your best health outcomes, so be sure to keep them up-to-date with any changes in how you feel.
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