Pituitary Adenoma: Symptoms, Causes & Treatment Canada

A pituitary adenoma is a benign (non-cancerous) tumour that develops on the pituitary gland, a small but powerful gland located at the base of your brain. These growths are the most common type of pituitary tumour, and while the diagnosis may sound alarming, the vast majority are not life-threatening and respond well to modern treatment. Understanding this condition is the first step toward getting the right care.

How Is a Pituitary Adenoma Diagnosed and Treated in Canada?

For Canadians navigating a new diagnosis, knowing the pituitary tumour symptoms to watch for and the treatment options available through our healthcare system can provide real peace of mind. This article explains what causes a pituitary adenoma, how doctors in Canada diagnose it, and the full range of treatments — from watchful waiting to surgery — so you can make informed decisions about your health.

What Is the Pituitary Gland?

Types of Pituitary Adenoma: Characteristics and Management Approaches

Type of Pituitary Adenoma	Key Characteristics	Common Symptoms	Primary Management
Prolactinoma	Most common type; secretes excess prolactin; more frequent in women aged 20–50	Irregular periods, galactorrhea, infertility, reduced libido	Dopamine agonist medications (cabergoline, bromocriptine); surgery if medication fails
Growth Hormone-Secreting Adenoma	Causes acromegaly in adults or gigantism in children; often diagnosed late due to gradual onset	Enlarged hands and feet, coarsened facial features, joint pain, excessive sweating	Transsphenoidal surgery; somatostatin analogues (octreotide); radiation therapy
ACTH-Secreting Adenoma	Triggers excess cortisol production; leads to Cushing’s disease; often small and difficult to detect on imaging	Weight gain (especially abdominal), stretch marks, high blood pressure, easy bruising	Transsphenoidal surgery as first-line; steroidogenesis inhibitors; radiation if surgery is incomplete
Non-Functioning Adenoma	Does not secrete active hormones; often detected incidentally or when large enough to cause mass effect	Headaches, vision changes, hypopituitarism symptoms due to compression	Watchful waiting for small tumours; surgery for large or symptomatic cases; regular MRI monitoring
TSH-Secreting Adenoma	Rarest functioning type; causes secondary hyperthyroidism; may be misdiagnosed as primary thyroid disease	Palpitations, weight loss, tremor, heat intolerance, goitre	Somatostatin analogues to reduce TSH secretion; transsphenoidal surgery; thyroid function normalization

The pituitary gland is about the size of a pea. It sits at the base of your brain, just behind your nose. Despite its small size, it is sometimes called the “master gland” because it controls many other hormone-producing glands throughout your body.

The pituitary gland works closely with a brain region called the hypothalamus. Together, they regulate your entire hormonal system. The gland produces several key hormones, including:

• Prolactin (PRL) — supports breast milk production
• TSH (thyroid-stimulating hormone) — controls the thyroid gland
• GH (growth hormone) — regulates growth and metabolism
• ACTH (adrenocorticotropic hormone) — controls stress hormones
• LH (luteinizing hormone) — involved in reproduction
• FSH (follicle-stimulating hormone) — involved in reproduction

When a tumour grows on this gland, it can disrupt the normal production of these hormones. This disruption leads to a wide range of symptoms throughout the body.

What Is a Pituitary Adenoma?

A pituitary adenoma is a tumour made of abnormal pituitary cells that multiply without control. These tumours do not spread to other parts of the body. However, they can still cause serious health problems by pressing on nearby brain structures or by overproducing hormones.

Doctors classify pituitary adenomas by their size:

• Microadenoma — smaller than 1 centimetre in diameter
• Macroadenoma — larger than 1 centimetre in diameter

They are also classified as secreting (they produce excess hormones) or non-secreting (they do not produce hormones but may still cause problems by pressing on nearby tissue). According to the Mayo Clinic’s overview of pituitary tumours, these growths are quite common and are often found incidentally during brain imaging done for other reasons.

Causes and Risk Factors

What Causes a Pituitary Adenoma?

The exact cause of a pituitary adenoma is not fully understood. Researchers believe that changes (mutations) in the DNA of pituitary cells cause them to grow out of control. These mutations mean the cells no longer respond to the body’s normal signals to stop dividing.

In most cases, these DNA changes happen randomly. They are not caused by anything the person did or did not do.

Known Risk Factors

Certain conditions can increase your chances of developing a pituitary adenoma. These include:

• Multiple Endocrine Neoplasia Type 1 (MEN1) — a genetic condition that causes tumours in multiple hormone-producing glands
• Carney Complex — a rare genetic disorder linked to tumours and skin changes
• Familial isolated pituitary adenoma (FIPA) — a hereditary tendency to develop pituitary tumours
• McCune-Albright Syndrome — a condition affecting bones, skin, and hormones

If you have a family history of any of these conditions, talk to your family doctor. They may refer you to an endocrinologist for monitoring. You can also learn more about hormonal disorders from Health Canada’s official health information resources.

Symptoms of a Pituitary Adenoma

Symptoms of a pituitary adenoma vary widely. They depend on the tumour’s size, whether it produces hormones, and which hormone it produces. Importantly, a small secreting tumour can cause more noticeable symptoms than a large non-secreting one.

Symptoms Caused by Tumour Size (Mass Effect)

When a tumour grows large enough, it presses on the pituitary gland and nearby brain structures. This pressure can cause:

• Headaches
• Blurred or double vision
• Loss of side (peripheral) vision
• Facial nerve weakness or paralysis
• Drooping eyelid (ptosis)
• Clear fluid draining from the nose

Symptoms from Excess Prolactin

About 40% of secreting pituitary adenomas produce too much prolactin. In women, this can cause:

• Unexpected breast milk production (not related to breastfeeding)
• Irregular or absent periods
• Vaginal dryness
• Reduced bone density or osteoporosis

In both men and women, high prolactin can lower sex drive. Men may also notice fertility problems or breast tissue growth.

Symptoms from Excess Growth Hormone

Too much growth hormone causes different effects depending on your age. In adults, it leads to acromegaly — a condition where hands, feet, and facial features gradually enlarge. In children, it can cause gigantism, meaning abnormally rapid growth in height. Other symptoms include excessive sweating and high blood sugar (hyperglycaemia).

Symptoms from Excess ACTH (Corticotropin)

When a pituitary adenoma produces too much ACTH, it triggers the adrenal glands to overproduce cortisol. This leads to a condition called Cushing’s disease. Symptoms include:

• Weight gain, especially around the abdomen and upper back (sometimes called a “buffalo hump”)
• A round, puffy face (sometimes called “moon face”)
• High blood pressure
• Easy bruising and thin skin
• Irregular periods
• Rapidly rising blood sugar levels

Symptoms from Excess TSH (Thyrotropin)

A pituitary adenoma that produces too much TSH overstimulates the thyroid gland. This leads to hyperthyroidism. Symptoms include rapid heartbeat, tremors, anxiety, weight loss, insomnia, and an enlarged thyroid gland (goitre).

Symptoms from Pituitary Insufficiency

A large tumour can compress the pituitary gland and actually reduce hormone production. This is called hypopituitarism. Symptoms of this hormone deficiency include:

• Slowed or stopped growth in children
• Delayed puberty
• Loss of facial hair in men
• Absence of pubic hair
• Inability to produce breast milk after delivery
• Low blood pressure
• Unexplained weight gain
• Difficulty concentrating
• Low blood sugar (hypoglycaemia)

How Is a Pituitary Adenoma Diagnosed?

Diagnosing a pituitary adenoma involves several steps. Your doctor will first review your medical history and symptoms. They will also perform a physical examination to look for signs of hormonal imbalance.

Blood and Hormone Tests

Blood tests measure the levels of hormones produced by the pituitary gland and related glands. These may include prolactin, TSH, free T4 (FT4), IGF-1, growth hormone, ACTH, testosterone, estradiol, and blood sugar levels. Abnormal results can point to a secreting tumour.

Imaging Tests

MRI (Magnetic Resonance Imaging) is the gold standard for diagnosing pituitary tumours. It gives detailed images of the gland and the surrounding brain tissue. A CT scan (computed tomography) may also be used to provide additional detail about the tumour’s structure and its relationship to nearby structures.

For more information on how these tests work, Healthline’s guide to pituitary tumours offers a helpful overview written for general readers.

Treatment Options for Pituitary Adenoma

Treating a pituitary adenoma usually involves a team of specialists. In Canada, this team typically includes an endocrinologist, a neurosurgeon, and an ophthalmologist. Your provincial health plan generally covers referrals to these specialists through your family doctor.

Watchful Waiting

Not every pituitary adenoma needs immediate treatment. If the tumour is small and not causing symptoms, your doctors may recommend monitoring it over time. This involves regular blood tests and repeat MRI scans. If symptoms worsen or the tumour grows, your care team will move to active treatment.

Medication

Medication is often the first line of treatment, especially for prolactin-producing tumours. The goals of medication are to:

• Reduce or stop the tumour’s hormone production
• Replace hormones that the compressed pituitary gland can no longer produce
• Shrink the tumour to relieve pressure on surrounding structures

Common medications include dopamine agonists (such as cabergoline or bromocriptine) for prolactinomas. Other drug types are used depending on which hormone is being overproduced.

Radiation Therapy

Radiation therapy may be recommended in specific situations. Your care team may suggest it when:

• Surgery cannot remove the entire tumour
• The tumour returns after surgery
• Medication does not shrink the tumour enough
• The tumour is in a location that makes surgery too risky

Modern techniques such as stereotactic radiosurgery (Gamma Knife) allow precise targeting of the tumour while minimising damage to healthy brain tissue.

Surgery

Surgery is the most common active treatment for pituitary adenomas that are causing significant symptoms. In most cases, surgeons use a minimally invasive approach called transsphenoidal surgery. They reach the tumour through the nose and sinuses, avoiding the need to open the skull. Recovery time is generally shorter with this approach. Open brain surgery is rarely needed but may be considered for very large or complex tumours.

When to See a Doctor

You should speak with your family doctor if you experience any of the symptoms described in this article, especially unexplained vision changes, persistent headaches, irregular periods, or sudden weight changes. These symptoms do not always mean you have a pituitary adenoma, but they deserve proper evaluation.

If you do not have a family doctor, a walk-in clinic is a good first step. The doctor there can arrange initial blood tests and refer you to a specialist if needed. Most provincial health plans in Canada cover specialist referrals, including visits to endocrinologists, at no direct cost to patients.

Seek emergency care immediately if you suddenly develop severe headache, sudden vision loss, or signs of extreme hormone disruption. These may indicate a rare but serious complication called pituitary apoplexy, where the tumour bleeds or loses its blood supply. Always consult your doctor before making any decisions about your health based on what you read online.

Frequently Asked Questions About Pituitary Adenoma